THE   SPIRIT   OF   THE   SOIL 


FIG.    I 


The  Grevilleas  shown  above  were  treated,   the  plant  on  the  left  with 

complete  chemical  manure  and  the  plant  on  the  right  with  humogen 

and  ordinary  soil.      J  he  freedom  of  the  side  growths,  apart  from 

remafkabl       impr°Ved  £rowth   of  the   humogen -treated   plant,   is 

(The  Royal  Gardens,  Kew.) 


Frontispiece 


THE 
SPIRIT  OF  THE  SOIL 

OR 

AN  ACCOUNT  OF  NITROGEN  FIXATION 

IN    THE     SOIL    BY    BACTERIA    AND    OF 

THE    PRODUCTION    OF   AUXIMONES    IN 

BACTERIZED  PEAT 

BY 

GORDON    D.    KNOX 

AUTHOR  OF 
"ALL  ABOUT  ENGINEERING,"  "ALL  ABOUT  ELECTRICITY,"  AND  "ENGINEERING" 

WITH  A  FOREWORD 

BY 

PROFESSOR  W.  B.  BOTTOMLEY 


'  Semina  vidi  equidem  multos  medicare  serentes 
Et  nitro  prius  et  nigra  perfundere  amurca 
Grandior  ut  fetus  siliquis  fallacibus  esset." 

VIRGIL:  Georgics,  1,  193-195 


S^CpND  .IMPRESSION,    . 

NEW  YORK 

FREDERICK   A.    STOKES   COMPANY 
PUBLISHERS 


Printed  in  Great  Britain 


FOREWORD 

THE  interest  aroused  in  bacterized  peat  during  the 
last  two  years  is  sufficient  reason  for  the  publication 
of  a  popular  book  dealing  with  the  recent  researches 
on  humus  formation,  nitrogen-fixation,  and  acces- 
sory plant-food  bodies  (auximones) .  Owing  to  pres- 
sure of  other  duties  I  had  neither  time  nor  oppor- 
tunity to  undertake  the  work  myself,  but  in  leaving 
this  task  to  my  friend  Mr.  Knox  I  had  every  confi- 
dence that  the  subject  would  neither  lose  in  accuracy 
of  fact  nor  in  the  interest  of  its  presentation. 

Mr.  Knox's  literary  ability,  combined  with  his 
scientific  training,  render  him  peculiarly  well  fitted 
to  write  a  book  popular  in  style,  yet  without  sacri- 
ficing the  scientific  side  of  the  subject.  Mr.  Knox 
has  submitted  to  me  the  manuscripts  of  the  various 
chapters,  and  it  is  a  pleasure  for  me  to  be  able  to 
say,  at  his  request,  that  I  can  take  full  responsibility 
for  all  the  results  which  he  has  described. 

I  can  confidently  recommend  Mr.  Knox's  book  as 
an  accurate  and  popular  exposition  of  a  new  develop- 
ment in  agriculture  and  horticulture  which  may  have 
an  important  bearing  on  the  national  food-supply. 

W.  B.  BOTTOMLEY. 

BOTANICAL  LABORATORIES, 
UNIVERSITY  OF  LONDON, 
KING.'S  COLLEGE. 


3593^7 


PREFACE 

THE  present  volume  is  the  outcome  of  the  keen 
personal  interest  that  I  have  taken  for  some  eight 
years  in  the  work  on  nitrogen-fixing  organisms  that 
has  been  in  progress  in  Professor  Bottomley's 
Laboratory  at  King's  College.  It  would  have  been 
difficult  for  me  to  write  of  the  subject  without  en- 
thusiasm. To  many  botanists  the  beauty  of  plant 
life  to  some  extent  masks  the  supreme  mysteries  of 
the  vegetable  world.  Few  conceptions  are  grander 
than  the  wonderful  storage  system  which  from  the 
beginning  of  biological  time  has  enabled  plant  life 
to  seize  and  hold  in  the  tissues  some  of  the  steady 
stream  of  energy  that  flows  continually  from  sun  to 
earth,  avoiding  waste,  steadily  purifying  the  air,  and 
rendering  its  composition  constant.  That  is  an  old 
conception  well  established  and  commonly  known. 
To-day,  however,  we  are  watching  the  growth  of  a 
new  conception.  Just  as  the  plants  have  been 
steadily  storing  the  energy  that  is  required  for  the 
support  of  animal  life,  and  making  existence  possible 
for  them,  so  the  bacteria  in  the  soil  have  been 
supplying  the  plants  with  the  essential  substances 
that  they  require  for  their  more  limited  activities. 
Nitrogen  as  such  is  valueless  to  plants.  Were  it  not 
for  the  work  of  the  bacteria  in  the  soil  no  plant  could 


viii  PREFACE 

win  a  livelihood,  for  it  is  only  when  the  abundant 
nitrogen  in  the  air  and  in  decaying  organisms  has 
been  combined  into  suitable  chemical  compounds 
that  it  becomes  available  as  a  plant  food.  The  work 
of  Professor  Bottomley  has  been  concerned  ex- 
clusively with  the  activities  of  these  organisms,  and 
his  object  has  been  to  find  a  means  for  giving  them 
an  environment  in  which  they  can  freely  develop. 
His  aim  has  been  in  fact  to  do  for  the  bacteria  the 
same  service  that  the  gardener  and  farmer  perform 
for  the  plants  that  they  cultivate.  Husbandry  is 
the  oldest  of  the  arts  and  sciences,  bacteriology  the 
youngest.  In  this  book  I  have  attempted  to  indicate 
some  of  the  results  that  will  certainly  follow  from 
soil  inoculation.  I  am  not  suggesting  that  Pro- 
fessor Bottomley  has  found  the  whole  truth,  that 
later  workers  will  not  achieve  the  results  that  he  can 
claim  by  more  suitable  methods.  I  think,  however, 
that  the  evidence  collected  in  the  following  pages 
will  convince  the  reader  that  a  notable  advance  has 
been  made  in  horticulture,  and  that  a  new  discovery 
of  momentous  consequence  has  been  made  in  the 
accessory  food  bodies  or  auximones,  a  discovery 
that  will  complete  and  round  off  the  corresponding 
discovery  of  vitamines  and  their  relation  to  the 
health  and  growth  of  animals.  Lastly,  I  have  pre- 
pared the  book  in  the  hope  that  farmers  and  gar- 
deners will,  as  they  alone  are  able  to  do,  carry  these 
experiments  into  the  wider  field  of  everyday  life. 
Farming  and  gardening  are  arts  requiring  expert 
knowledge.  It  is  only  reasonable  to  suppose  that 
laws  and  conditions,  comparable  with  those  governing- 


PREFACE  ix 

the  growth  of  plants,  maintain  for  bacteria.  The 
work  of  Professor  Bottomley  opens  up  an  oppor- 
tunity for  every  gardener  and  for  every  farmer  to 
undertake  important  scientific  work,  and  at  the 
same  time  almost  certainly  to  increase  very  con- 
siderably the  yield  from  his  land.  Such  work  is  of 
the  very  first  national  importance  and  of  world-wide 
interest.  It  is  certain  that  one  of  the  most 
important  factors  in  the  fertility  of  all  land  is  the 
nature  of  the  bacteria  in  the  soil.  In  every  depart- 
ment of  life  man,  by  assisting  Nature,  has  been 
generously  rewarded.  The  science  of  bacteriology 
both  in  medicine  and  in  the  arts  has  very  richly 
repaid  the  labour  spent  on  it.  It  is  inconceivable 
that  horticulture  and  agriculture  should  prove 
exceptions  to  the  general  rule. 

In  the  preparation  of  this  book  I  have  to  acknow- 
ledge much  assistance.  To  Professor  Bottomley 
and  his  writings  I  am  indebted  exclusively  for  my 
knowledge  of  his  work  and  for  the  major  part  of 
what  I  know  about  the  subject  in  general.  During 
the  years  that  I  have  known  him  he  has  at  all  times 
given  me  access  to  his  laboratory  and  to  the  reports 
that  have  been  sent  in  to  him.  Throughout  he  has 
inspired,  read,  and  criticized  the  manuscript  of  the 
book.  I  also  owe  much  to  Mr.  Alfred  Machen,  who 
has  shown  and  explained  to  me  many  of  the  experi- 
ments now  in  progress  on  the  land.  The  chapters 
on  the  General  Results  from  the  use  of  humogen,  on 
the  Application  of  Humogen,  and  the  practical  hints 
in  conclusion,  are  due  entirely  to  him.  Miss  Mocke- 
ridge,  by  her  valuable  criticism,  has  saved  me  from 


x  PREFACE 

many  errors,  and  helped  me  most  materially  in  the 
general  chapter  on  chemistry. 

I  have  to  thank  the  Editors  of  several  papers  for 
leave  to  make  use  of  material  published,  notably 
the  Editors  of  the  Proceedings  of  the  Royal  Society, 
and  the  Edinburgh  Medical  Journal y  the  Annals 
of  Botany,  the  Journal  of  the  Royal  Society  of  Arts, 
the  Biochemical  Journal,  and  Country  Life.  The 
Editor  of  the  Morning  Post  has  kindly  allowed  me 
to  use  the  papers  on  the  "  National  Food  Supply," 
contributed  by  Mr.  Charles  W.  Fielding.  I  have  to 
thank  that  gentleman  and  Dr.  N.  L.  Watson-Wemyss 
for  the  ready  permission  they  gave  me  to  make  use 
of  their  writings.  I  have  consulted  several  books 
in  the  course  of  my  work,  particularly  The  Geological 
Survey  of  Ohio,  by  Dr.  Alfred  Dachnowski;  The 
Soil,  by  Dr.  A.  D.  Hall;  Bacteria  in  Relation  to 
Country  Life,  by  Dr.  Jacob  G.  Lipman ;  and  Soil  Con- 
ditions and  Plant  Growth,  by  Dr.  Edward  J.  Russell. 
I  have  also  to  thank  the  Editors  of  those  papers 
which  I  have  quoted  in  the  text  for  permission  to 
make  use  of  the  extracts  that  have  appeared  in 
their  columns. 

In  typing  the  manuscript  of  the  book  Mrs. 
Marshall  and  her  staff  have  very  materially  assisted 
me  by  their  promptness  and  accuracy. 

GORDON  D.  KNOX. 

u,  GARRICK  STREET,  W., 
August  9,  1915. 


CONTENTS 

CHAPTER  PAGE 

I.    THE   NITRATE   PROBLEM  I 

ii.  ENGLAND'S  FOOD-SUPPLY  IN  PEACE  AND  WAR     -  n 

III.  BACTERIA   AND   PROTOZOA                -                 -  IQ 

IV.  PEAT  AND   ITS   USES            -                 -                 -                 "31 
V.    FIXATION    OF   NITROGEN  BY  LEGUMINOUS  PLANTS  46 

VI.    HUMUS       ...  64 
VII.    BACTERIZED       PEAT   I       ITS      PREPARATION       AND 

GENERAL   PROPERTIES                 -                 -  8 1 
VIII.    VITAMINES,  ACCESSORY  FOOD  BODIES,  AND  AUXI- 

MONES                 -                 -                 -                 -  96 
IX.    ELEMENTARY    CONCEPTIONS     OF     CHEMISTRY     IN 

RELATION   TO   THE   SOIL             -                 -                 -  IIQ 

X.    THE   TESTING   OF   HUMOGEN             -                 -                 -  135 

XI.    THE   PREPARATION    OF   HUMOGEN                   -                 -  150 

XII.    PRESS   AND    OTHER   CRITICISM        ...  155 

XIII.  HOW   HUMOGEN    IS    APPLIED                               -                 -  169 

XIV.  GENERAL   RESULTS                                                                        -  1 78 
XV.    HINTS   AND   EXPERIMENTS                ...  197 

APPENDICES             .....  205 

LIST   OF  PAPERS   -                 ....  239 

INDEX        ......  241 


LIST  OF  ILLUSTRATIONS 

FIG. 

1.  GREVILLEA  FROM   KEW  GARDENS    -  -        Frontispiece 

2.  EFFECT   OF   HUMOGEN   ON   LILIES    -  -     FACING  PAGE  g 

3.  BACILLUS    RADICICOLA  -  -  -  53 

4.  AZOTOBACTER   CHROOCOCCUM  -  -  53 

5.  PRIMULA    TREATED    WITH   AUXIMONES          -  -58 

6.  HUMOGEN  CONTRASTED  WITH  LOAM  AND  COMPOST        60 

7.  HYACINTHS    TREATED    AND    UNTREATED       -  "91 

8.  AN   INSTANCE   OF  INCREASED   VARIEGATION  -      143 

9.  A   TOMATO   PLANT  -  -  -  -  -145 

10.  POTATOES   GROWN   IN   MOSS                -                 -  -  146 

11.  ROOT   DEVELOPMENT              -                 -                 -  -  159 

12.  INFLUENCE   OF  HUMOGEN   ON   BARLEY         -  -  165 

13.  CARNATIONS   IN   INFECTED   SOIL      -  -  1 66 

14.  TWO   BEAN   PLANTS                 -                 -                 -  -  183 

15.  MAIZE  PLANTS,  SHOWING  EFFECT  OF  AUXIMONES  -  191 

1 6.  A   CONTRAST   IN   RADISHES  ...  Tg^ 

17.  PRIMULA   KEWENSIS                -                 -                 -  -  212 


THE  SPIRIT  OF  THE  SOIL 

CHAPTER  I 

THE  NITRATE  PROBLEM 

Geometric  progression  illustrated  by  bacterial  growth — Geo- 
metric character  of  advancing  civilization — Latter-day 
developments — Present  prosperity — Threatened  famine  in 
power  and  nitrates — Science  to  the  rescue — Sources  of 
plant  food — Cavendish  and  Bunsen — Electrically  produced 
nitrates  —  A  nitrate  balance  -  sheet  —  The  outlook  —  In- 
creased demand — Diminished  supply  threatened — Bacteria 
as  nitrate  builders — Their  use  in  agriculture. 

PICTURE  an  observer  suspended  above  the  equator 
of  the  earth,  unaffected  by  the  swirl  due  to  the 
earth's  turning  on  her  axis,  but  following  closely 
her  movements  through  space.  Assume  that  at  an 
instant  in  time  he  drops  a  bacterium  on  the  hurry- 
ing surface  beneath  his  feet,  and  that  the  bacterium, 
like  the  seed  of  the  sower  that  fell  on  fruitful  ground, 
falls  into  a  medium  ideal  for  its  growth  and  finds 
nothing  to  check  its  power  of  reproduction.  In 
twenty-four  hours,  when  the  same  spot  of  the 
earth's  surface  was  again  beneath  his  feet,  he  would 
find,  instead  of  the  single  bacterium  he  had  dropped, 
a  bacterial  empire  one  hundred  and  seventy  thousand 
times  as  numerous  as  the  present  human  population 

i 


2  THE  SPIRIT  OF  THE  SOIL 

of  ;<.he  \vcrVl.;3t  If  tho  bacterium  were  the  anthrax 
bacillus,  and  the  members  were  well  developed,  the 
length  of  each  might  be  the  five-thousandth  part  of 
an  inch,  and,  had  they  developed  end  to  end  in  a 
long  chain  during  the  short  twenty-four  hours  spent 
by  the  earth  in  turning  on  her  axis,  the  progeny  of 
the  original  anthrax  bacillus  would  have  engirdled 
the  equator  thirty-seven  times,  welded  into  a  chain 
close  on  a  million  miles  in  length.  The  vaunted 
achievement  of  Ariel  engirdling  the  earth  fades  to 
nothingness  beside  the  astounding  energy  shown 
by  the  bacteria  in  their  passionate  longing  to  per- 
petuate their  kind.  The  facts  of  bacterial  growth 
stagger  the  imagination,  but,  like  most  things 
measurable,  they  have  been  brought  into  some  sort 
of  order,  and  expressed  and  fixed  in  rows  of  figures 
by  the  mathematician.  Marvellous  as  is  the  state- 
ment made  above,  even  the  enlightened  schoolboy 
of  to-day  would  see  little  to  wonder  at  in  it.  Was 
he  not  as  a  child  fresh  from  home  tricked  into 
attempting  to  estimate  the  value  of  the  nails  in  a 
horse's  shoe  when  the  first  nail  was  priced  at  a 
farthing,  the  second  at  a  halfpenny,  the  third  at  a 
penny,  and  so  to  the  last  nail,  and  did  he  not  give  up 
the  problem  in  despair  ?  Since  then  he  has  laboured 
through  the  mysteries  of  the  geometric  progression 
and  realized  something  of  the  magic  of  numbers. 

What,  however,  if  it  should  turn  out  that  in  our 
civilization  to-day  we  have  something  comparable 

*  "  With  division  occurring  every  half-hour,  a  single  individual 
could  become  in  one  day  the  ancestor  of  280,000,000,000,000  bac- 
teria "  (Dr.  Jaoob  B.  Lipman,  Bacteria  in  Relation  to  Country 
Life}. 


THE  NITRATE  PROBLEM  3 

with  a  geometric  progression  ?  There  are  some  who 
would  have  us  believe  that  the  history  of  the  earth 
is  a  succession  of  cycles,  that  civilization  attains  to  a 
certain  point,  and  then,  like  Sisyphus's  stone,  falls 
back  to  the  bottom  of  the  hill,  only  to  be  rolled  up 
it  again  by  toilsome  effort.  With  such  a  conception 
I  have  no  concern  here.  Inevitably,  recorded  his- 
tory tells  us  nothing  of  it.  In  any  case  we  can  know 
of  nothing  except  a  small  portion  of  the  hill  up  which 
we  have  been  ascending,  but  the  study  of  that  small 
portion  of  the  hill  is  amply  sufficient  to  stimulate  our 
imagination,  and  may  be  to  arouse  our  alarm. 

Quite  early  in  the  history  of  the  world  we  can 
glimpse  at  the  material  origins  of  civilization.  Even 
to-day  there  are  great  areas  where  the  road  exists 
only  in  the  primitive  form  of  the  track,  where  the 
wheel  is  unknown;  tradition,  wrongh  perhaps,  has 
brought  down  to  us  the  tale  of  when  and  how  the 
wedge  and  the  screw  were  first  devised  as  aids  to 
man's  enterprise.  As  we  glance  back  over  the  pages 
of  history  a  matter  of  some  three  thousand  years 
we  seem  to  see  something  in  it  which  suggests  that 
the  world's  progress  is  a  geometric  progression,  and 
that  we  are  at  a  point  to-day  when  each  doubling  of 
the  terms  in  the  series  involves  the  most  formidable 
consequences.  Can  we  realize  that  in  the  thirteenth 
century  lumps  of  coal  were  being  given  to  the  poor 
in  Scotland  as  alms,  and  that  as  recently  as  1735  the 
coal  consumption  of  England  attained  only  two 
million  tons  in  the  year  ?  Do  we  appreciate  the 
fact  that  it  is  not  until  1925  that  we  shall  celebrate 
the  centenary  of  the  first  steam  railway,  that  it 


4  THE  SPIRIT  OF  THE  SOIL 

was  not  until  1878  that  the  electric  dynamo  became 
a  practical  machine  ?  In  ancient  Greece  the 
mariner  who  voyaged  as  far  as  the  Pillars  of  Hercules 
in  Spain  was  a  traveller  expected  to  bring  back 
stories  of  monsters  and  other  wonders,  but  to-day 
there  is  not  a  portion  of  the  earth's  surface  which  is 
not  more  or  less  exactly  mapped. 

Despite  the  poverty  of  the  world,  we  are  for  the 
moment  living  in  a  period  of  abundance,  as  witness 
the  violence  of  the  attacks  made  upon  Malthus, 
who  wrote  at  a  period  when  it  seemed  that  man  had 
reached  the  limits  of  his  food-supplies.  Between 
then  and  now  intensive  agriculture  has  arisen  as  a 
new  art ;  the  great  granaries  of  the  world  have  been 
available  for  all,  thanks  to  the  development  of  the 
vast  transport  agencies.  The  mighty  deposits  of 
nitrates  in  Chili  and  Peru,  Stassfurt,  and  elsewhere, 
have  been  mined  to  provide  the  farmer  with  the 
necessary  fertilizers,  and  at  the  moment  the  supply 
is  ample  for  the  world's  needs. 

Those  who  care  to  look  forward  to  the  world's 
future,  however,  are  uttering,  Cassandra-like,  doleful 
prophecies.  The  inroads  made  on  the  great  forests 
of  the  United  States,  especially,  have  been  so  serious 
that  the  world  is  called  upon  to  face  the  danger  of  a 
timber  famine.  Commissions  have  been  appointed 
to  estimate  how  long  we  may  expect  the  coal  reserves 
which  are  being  worked  at  a  rapidly  progressive 
speed  to  continue  to  furnish  their  abundant  energy 
to  the  world.  It  is  recognized  that  the  time  will 
come,  and  is  not  so  very  far  distant,  when  Canada, 
the  United  States,  and  the  other  great  wheat-pro- 


THE  NITRATE  PROBLEM  5 

ducing  countries  of  the  world,  will  be  unable  to  furnish 
more  food  than  they  require  for  their  own  con- 
sumption. It  was  Sir  William  Crookes,  now  Presi- 
dent of  the  Royal  Society,  who  as  President  of  the 
British  Association  first  startled  the  world  by  warn- 
ing it  of  the  menace  to  its  food-supply.  The  in- 
creased control  gained  by  man  over  Nature — a 
geometrically  increased  control — has  enabled  him 
to  draw  on  the  capital  stored  in  the  ground  to  an 
extent  unthought  of  by  his  ancestors,  and,  like  the 
proverbial  nouveau  riche,  he  has  been  squandering 
the  treasure  to  which  he  has  gained  access.  Appetite 
has  come  with  eating.  The  treasures  that  at  first 
seemed  inexhaustible  are  now  harder  to  win  than 
they  were,  are  now  showing  signs  of  becoming 
exhausted,  and  Nature  is  threatening  to  return  our 
spendthrift  cheques  to  us  marked  with  the  red  ink 
comment,  "  No  effects." 

Experimental  science,  when  this  day  arrives, 
promises  to  treat  us  rather  as  an  indulgent  guardian 
than  as  a  hard-hearted  money-lender.  There  is 
happily  in  the  sun  a  portion  of  an  estate  that  we 
have  been  able  neither  to  sell  nor  to  mortgage,  and 
when  Sir  William  Crookes  startled  us  into  taking 
stock  of  our  resources,  the  men  of  science  set  to  work 
to  see  whether  it  might  not  be  possible  to  make  a 
better  use  of  our  yearly  income  than  under  the 
influence  of  an  apparently  unlimited  capital  we  had 
been  doing  in  the  past.  Two  foodstuffs  in  bulk  are 
necessary  for  the  life  of  plants,  Carbon  and  Nitrogen. 
The  first  is  omnipresent  in  the  air,  and  under  the 
influence  of  sunlight  the  plants  from  the  earliest 


6  THE  SPIRIT  OF  THE  SOIL 

times  have  seized  it  in  the  form  of  Carbon  dioxide, 
and  changed  it  in  their  leaves  to  the  form  in  which 
they  could  assimilate  it.  The  second,  Nitrogen,  is 
also  present  in  the  air,  but  in  such  a  form  that  no 
plant  is  able  to  assimilate  it  or  to  combine  it  so  as 
to  render  it  available  for  its  use.  Sir  William 
Crookes  put  the  problem  clearly  and  succinctly. 
Either  the  world  in  thirty  or  forty  years  from  the 
date  of  his  address  was  doomed  to  suffer  from  a 
wheat  famine  unexampled  in  the  history  of  the 
world,  or  it  was  incumbent  on  the  man  of  science 
to  find  a  practical  means  of  inducing  the  inert  nitro- 
gen of  the  air  to  enter  into  combination  with  oxygen, 
and  form  the  nitrates  essential  for  plant  food. 

There  was  one  outstanding  classical  experiment 
to  guide  the  chemists  in  their  elucidation  of  the 
problem.  In  1785  Cavendish  discovered  that  when 
an  electric  current  was  passed  through  air  an  acid 
was  formed,  and  seventy-two  years  later  Bunsen 
established  that  the  acid  so  formed  was  Nitric  Acid, 
the  Oxygen  and  Nitrogen  of  the  air  having  been 
induced  by  means  of  the  energy  of  the  electric  dis- 
charge to  enter  into  combination  to  form  the  acid- 
On  this  groundwork  the  chemists  set  to  work,  and  in 
a  few  years'  time  they  had  devised  a  practical  method 
whereby  the  water-power  of  the  great  waterfalls 
could  be  used  to  produce  a  high-tension  electric 
current.  The  current  was  allowed  to  discharge 
across  a  gap,  was  spread  out  by  means  of  a  powerful 
magnet  into  a  great  disc  of  blazing,  roaring  flame, 
which,  on  air  being  forced  through  it,  induced  the 
Nitrogen  and  Oxygen  present  to  enter  into  combina- 


THE  NITRATE  PROBLEM  7 

tion.  By  this  and  by  other  methods  the  chemists 
have  achieved  a  partial  solution  for  Sir  William 
Crookes's  problem.  For  they  have  found  a  method, 
dependent  on  income  and  not  on  capital,  whereby 
the  nitrates  required  for  agriculture  can  be  produced 
at  a  cost  that  enables  them  to  compete  successfully 
with  the  nitrates  prepared  from  natural  deposits. 

The  achievement  is  one  of  which  the  chemists  may 
well  be  proud,  but  after  all  it  is  only  a  partial  solution. 
We  were  threatened  by  Sir  William  Crookes  with  a 
nitrogen  famine,  but  since  then  men  of  science  have 
threatened  us  with  an  even  more  serious  danger,  an 
energy  famine.  At  present  in  coal  we  have  an 
abundant  supply  of  energy  available  at  a  low  cost, 
but  when  this  begins  to  give  out  the  value  of  water- 
power  must  advance  by  leaps  and  bounds,  and  force 
up  with  it  the  cost  of  the  manufactured  nitrates  to 
such  a  point  that  the  farmer  will  be  unable  effectively 
to  compete  with  the  other  potential  users  of  power. 

We  are  brought  back  therefore  to  a  reconsideration 
of  the  problem,  and  it  may  prove  of  value  briefly  and 
roughly  to  formulate  it  in  tabular  form  as  follows : 

Demand  for 
Nitrates.  Sources  of  Supply. 

Agriculture     . .     Nitrate    deposits    (already    showing    signs   of 
exhaustion) . 

Explosives       . .     Chemical  means  (in  all  of  these  the  utilization 
of  power  on  a  large  scale  is  essential) . 

Various  . .     Farmyard  manure,  sewage,  etc.  (a  decreasing 

source,   which  in  some  cases  will  not  pay 
the  cost  of  collection). 

Bacteria  (as  in  those  associated  with  leguminous 
plants,  and  as  those  cultivated  by  the  new 
system  of  treating  peat).  These  are  only 
indirectly  a  source  of  nitrates,  as  they  form 
complex  nitrogenous  food  substances  rather 
than  actual  nitrates. 


8  THE  SPIRIT  OF  THE  SOIL 

There  seems  no  reason  to  believe  that  there  can 
ever  be  a  lessened  demand  for  nitrates.  With  the 
continued  increase  both  of  population  and  of 
standard  of  comfort,  and  with  the  rapid  exhaustion 
of  the  virgin  soils  that  were  to  be  met  with  in  the 
early  days  of  farming  in  America  and  Canada,  the 
drain  made  on  the  world's  stock  of  nitrates  by  agri- 
culture must  continue  to  increase;  the  present  war 
indicates  that  the  demand  made  by  explosives  for 
munitions  of  war  will  be  more  than  maintained,  while 
great  engineering  works  will  probably  absorb  more 
than  in  the  past.  Lastly,  with  the  increased  activity 
of  the  chemical  trade  it  seems  inevitable  that  in  this 
direction,  too,  a  further  increase  in  the  production  of 
the  world's  nitrates  will  be  essential. 

From  the  standpoint  of  supply  the  situation  at 
first  sight  does  not  seem  promising.  As  Sir  William 
Crookes  pointed  out,  the  exhaustion  of  the  natural 
deposits  is  already  in  sight,  and  there  seems  no  valid 
reason  for  believing  that  new  sources  of  nitrates  will 
be  discovered  to  replace  the  old.  Chemical  pro- 
ducers of  nitrates  will  before  long  find  themselves  in 
serious  competition  with  other  users  of  power.  With 
the  introduction  of  the  motor  car  farmyard  manure 
will  become  less  and  less  available,  while  at  present  it 
has  seldom  proved  practicable  to  utilize  the  waste 
sewage  produced  in  the  great  towns.  As  one  writer 
has  expressed  it,  it  is  no  more  reasonable  to  quarrel 
with  the  farmer  for  not  utilizing  the  sewage  of  the 
towns  than  it  is  to  quarrel  with  the  manufacturers 
for  not  collecting  and  burning  the  vast  masses 
of  carbon  that  are  poured  out  daily  from  the 


FIG.   2 

The  left  of  the  two  lilies  shown  above  was  grown  in  humogen  and 
ordinary  soil,  while  that  on  the  right  was  grown  in  a  complete  food 
compost.  The  average  number  of  blooms  on  the  batch  (48  size 
pots)  was  six  as  against  four,  and  it  should  be  noted  that  this 
is  the  common  effect  of  humogen  treatment  on  bulbs. 
(The  Royal  Gardens,  Kew.) 


THE  NITRATE  PROBLEM  9 

private  chimney-pots  of  householders  in  the  great 
cities. 

There  remains  one  great  source  of  nitrates  and  a 
great  army  of  workers  adapted  from  the  beginning 
of  time  for  the  fundamental  work  of  nitrate  pro- 
duction, fitted  for  that  work  and  that  work  alone, 
an  army  of  workers  that  require  only  the  intelligent 
co-operation  of  the  farmer  and  the  man  of  science 
efficiently  to  perform  their  duties — the  bacteria  of 
the  soil.  It  is  the  purpose  of  this  book  to  show  how 
an  English  man  of  science  working  in  an  English 
laboratory  has  set  out  to  solve  the  problem  of 
facilitating  the  work  of  the  soil  bacteria,  how  the 
experiments  carried  out  in  laboratory,  hothouse 
and  field,  all  go  to  prove  that  the  bacteria  of  the 
soil  intelligently  applied  cause  a  growth  of  crops 
heavier  than  that  obtained  by  manures  owing  to 
the  steady  supply  of  nitrogen  that  they  furnish  to 
the  plants,  and  owing  to  the  potash  and  phosphate 
that  they  render  available,  and,  lastly,  how  in  the 
course  of  his  researches  he  has  been  forced  to  believe 
in  the  existence  and  potency  of  certain  mysterious 
accessory  food  substances  produced  through  the 
action  of  the  bacteria,  which  bring  about  a  develop- 
ment of  plant  life  unparalleled  by  any  manure 
hitherto  known,  whether  natural  or  artificial. 

I  have  no  wish  that  these  statements  should  be 
accepted  on  the  ipse  dixit  of  the  workers  themselves, 
or  of  those  who  have  conducted  field  experiments. 
In  the  following  pages  the  attempt  will  be  made  to 
describe  simply  the  laboratory  results  of  the  last 
eight  years'  work  at  the  Botanical  Laboratories  of 


io  THE  SPIRIT  OF  THE  SOIL 

the  University  of  London  King's  College.  At  the 
same  time  an  account  will  be  given  of  the  results 
obtained  in  the  field.  I  shall  describe,  too,  what  I 
have  seen  myself  in  some  stations  at  which  large 
scale  experiments  are  now  in  progress,  and  in  con- 
clusion I  shall  give  in  their  own  words  the  opinion  of 
practical  agriculturists  on  the  material  used  and  the 
results  that  they  have  obtained.  On  these  bases, 
and,  if  need  be,  on  experiments  conducted  by  himself, 
each  man  will  decide  for  himself  whether  or  not  the 
saving  of  the  present  situation  and  the  future  of 
agriculture  rests  with  the  bacteria  of  the  soil.  For 
my  own  part  I  have  no  uneasiness  as  to  the  verdict. 


CHAPTER  II 

ENGLAND'S  FOOD-SUPPLY  IN  PEACE  AND  WAR 

Laisser-aller  policy — Two  months'  famine  margin — Wheat- 
growing  in  England  and  abroad — Wheat  imports — Decay 
of  wheat-growing  in  England — Increased  acreage  yield 
abroad — Stagnation  in  stock-raising — Inevitable  wheat 
shortage — Redistribution  of  crops  suggested — Difficulties  of 
the  scheme — The  competition  for  nitrates. 

BITTER  experience  gained  in  the  present  war  is 
forcing  home  the  lesson  that  too  heavy  a  price  may 
be  paid  for  the  pursuing  of  an  easy-going  policy  of 
go-as-you-please.  Were  the  price  demanded  only 
that  of  British  treasure,  the  non-organization  of  the 
country  would  be  stupid  and  suicidal.  But  the  cost 
of  it  to-day,  as  we  have  had  to  read  the  reckoning, 
is  the  lives  of  our  fellow-men  sacrificed  to  our  past 
blindness  and  the  unspeakably  grave  peril,  not  yet 
for  a  certainty  surmounted,  that  Britain  may  be 
humbled  to  the  dust  through  famine. 

The  voices  of  those  preaching  agricultural  reform 
are  the  voices  of  men  crying  in  the  wilderness,  calling 
attention  to  a  risk  as  grave  as  that  which  Lord 
Roberts  was  never  tired  of  voicing ;  but  the  country 
closes  its  ears  to  those  who  tell  it  of  the  risk  just 
as  they  callously  ignored  the  need  of  anything 
approaching  national  service. 

ii 


12  THE  SPIRIT  OF  THE  SOIL 

It  is,  however,  notorious  that  Great  Britain  lives 
from  day  to  day  with  a  margin  of  but  two  months 
between  her  and  famine.  Let  the  seas  be  closed 
only  for  that  period  to  merchant  vessels,  or  let  the 
nations  that  send  her  their  corn  from  the  harbours  of 
the  Seven  Seas  be  unable  to  launch  their  supplies, 
and  the  price  of  wheat  will  mount  by  leaps  and 
bounds  until  the  poorer  classes  of  the  country  will 
find  it  impossible  to  buy  a  loaf  of  bread.  This  is  the 
tragic  side  of  the  picture,  but  on  other  grounds  than 
those  of  the  immediate  national  danger  the  situation 
calls  for  reform.  It  is  not  the  truth  that  English 
land  is  unsuited  for  wheat-growing,  or  that  the  great 
percentage  of  the  land  is  inferior  to  that  cultivated 
in  France  or  Germany.  The  problem  exists  in  an 
equally  acute  form  as  regards  stock-raising,  and 
in  that  connection  is  no  less  urgent  in  demanding 
a  solution.  And  from  both  standpoints  the  issue  is 
bound  up  with  soil  fertility. 

Few  who  are  not  expert  agriculturists  can  have 
any  conception  of  the  vast  discrepancy  between  the 
conditions  prevailing  in  England  and  those  obtaining 
abroad.  The  situation,  however,  has  been  carefully 
studied  and  explained  by  several  observers,  notably 
in  the  early  months  of  this  year  by  Mr.  C.  W.  Fielding 
in  the  columns  of  the  Morning  Post,  and  it  is  from 
his  articles  based  on  official  figures  that  the  chief 
conclusions  of  the  present  chapter  are  drawn. 

In  agricultural  produce  England  buys  from  abroad 
the  enormous  total  of  £333,000,000  worth  of  im- 
ported soil  products,  a  value  £133,000,000  greater 
than  the  total  manufacturing  exports,  once  deduction 


ENGLAND'S  FOOD-SUPPLY 


is  made  of  the  cost  of  the  raw  material  imported  in 
connection  with  their  manufacture.  The  first  ques- 
tion naturally  arising  out  of  this  statement  is  how  far 
this  volume  of  imports  is  a  necessary  condition  of 
England  being  a  manufacturing  country,  and  a  pro- 
visional answer  is  given  most  simply  by  a  comparison 
between  the  conditions  in  the  United  Kingdom, 
France  and  Germany. 


United 

Kingdom. 

Germany. 

France. 

Total  acreage  under  cul- 

tivation 

48,000,000 

86,000,000 

67,000,000 

Of  which  acreage  under 

plough 
Of  which  acreage  under 

20,000,000 

65,000,000 

47,000,000 

grass  

28,000,000 

21,000,000 

20,000,000 

Percentage  of  cultivated 

surface  in  grass 

60  per  cent. 

60  per  cent. 

30  per  cent. 

Acres     growing     bread 

grain 

1,791,000 

20,000,000 

19,500,000 

Percentage  of  total  culti- 

vated   area    growing 

bread  grain,  about  .  . 

3  per  cent. 

25  per  cent. 

30  per  cent. 

Total     quarters     bread 

grain  produced 

7,000,000 

73,000,000 

47,000,000 

Production     of      bread 

grain     per     head     of 

population 

90  pounds 

485  pounds 

500  pounds 

Head  of  cattle 

11,000,000 

20,000,000 

14,000,000 

Population 

45,000,000 

65,000,000 

40,000,000 

Population   engaged   in 

agriculture 

1*350,000 

10,000,000 

8,000,000 

Percentage    of    popula- 

tion engaged  in  agri- 

culture 

3  per  cent. 

1  7  per  cent. 

20  per  cent. 

Bushels      bread     grain 

produced  per  acre  of 

total  arable  land 

3 

9 

8 

Acres    grass    used    per 

head  cattle,  about   .  . 

3 

i 

ii 

THE  SPIRIT  OF  THE  SOIL 


These  statistics  are  startling  to  anyone  who  has 
the  interests  of  the  nation  at  heart,  and  the  dis- 
crepancy between  the  practice  of  Great  Britain  and 
that  of  her  great  Continental  neighbours  stimulates 
a  further  inquiry.  There  is  a  grave  challenge  to 
British  farming  in  the  statement  that  only  3  per  cent, 
of  our  cultivated  land  is  employed  in  growing  wheat 
as  opposed  to  25  per  cent,  in  Germany  and  30  per 
cent,  in  France. 

The  conditions  have  not  always  been  the  same  as 
they  are  to-day,  and  the  gravity  of  the  problem  is 
emphasized  more  clearly  by  a  further  comparison 
made  with  other  countries.  During  the  last  thirty 
years  in  the  countries  mentioned  below  the  total 
acreage  under  cultivation  has  varied  little,  but  the 
attention  paid  to  the  growing  of  wheat  has  enor- 
mously increased  everywhere  except  in  England* 
where  there  has  been  a  large  fall  in  output,  as  is 
shown  from  the  following  table : 


Germany  has  increased  her  wheat  production 

France 

Russia 

Hungary 

Roumania 

Bulgaria 


25  per  cent. 

7 
90 

25 

33 

22 


While  the  output  of  the  United  Kingdom  has  fallen  30 

An  attractive  explanation  of  the  situation  would 
be  that  the  pressure  of  population  in  other  countries 
had  forced  into  wheat  cultivation  land  unsuited  for 
it,  and  that  the  increased  acreage  and  increased 
gross  yield  on  the  Continent  was  only  obtained  by 
sacrifices  of  such  an  order  that  the  farmers  of  this 
country  did  not  care  to  follow  suit.  An  analysis  of 


ENGLAND'S  FOOD-SUPPLY 


the  figures,  however,  shows  a  further  disquieting 
result.  During  the  period  considered  the  yield  of 
wheat  per  acre  in  the  United  Kingdom  has  remained 
absolutely  stationary,  while  in  those  countries  that 
have  increased  their  acreage  under  wheat  the  yield 
has  risen  from  between  15  to  40  per  cent.  The 
following  is  the  detailed  comparison : 


In  Germany  the  yield  has  gone  up 

In  France 

In  Russia 

In  Hungary 

In  Roumania 

In  Bulgaria 


40  per  cent. 

18 

20 

15 

20 
25 


Perhaps  it  may  be  thought  Great  Britain  makes 
up  for  her  deficiencies  as  a  wheat-grower  by  a  marked 
predominance  in  stock-raising.  The  facts  unfortu- 
nately are  otherwise,  as  the  figures  again  show : 


In  forty  years  the  German  stock  of 

cattle  has  increased  from    . . 
And  pigs  from 
France:  Increase  of  cattle  from 

Increase  of  pigs  from 
Belgium :  Increase  of  cattle  from 

Increase  of  pigs  from 
Hungary :  Increase  of  cattle  from 

Increase  of  pigs  from 

The  United  Kingdom  has  increased  cattle  only  from  10,000,000 
to  11,000,000;  while  the  stock  of  pigs  remains  practically  the 
same — viz.,  under  4,000,000. 


15,000,000  to  20,000,000 
7,000,000  to  22,000,000 

11,000,000  to  14,000,000 
5,000,000  to  7,000,000 
1,200,000  to  1,800,000 
600,000  to  1,300,000 
5,000,000  to  7,000,000 
4,000,000  to  7,500,000 


In  normal  times  the  situation  is  a  grave  one  for  the 
nation,  but  in  view  of  the  European  War  it  offers  a 
menace  of  exceptional  gravity.  Let  us  assume,  as  we 
have  now  perhaps  a  right  to  assume,  that  the  allied 
navies  will  preserve  the  freedom  of  the  seas  as  mag- 
nificently inviolate  to  the  end  of  the  war  as  they  have 
done  during  the  first  twelve  months  of  it,  and  that  we 


16  THE  SPIRIT  OF  THE  SOIL 

have  therefore  no  reason  to  fear  any  artificial  stop- 
page of  our  overseas  supplies.  The  Navy,  despite 
its  success,  cannot  influence  the  shortage  in  corn- 
stuffs  that  has  been  brought  about  inevitably  owing 
to  the  war. 

As  Mr.  Fielding  points  out,  it  is  the  richest  wheat 
area  of  France  that  has  suffered  German  invasion; 
East  Prussia  and  Galicia,  both  of  which  have  suffered 
invasion,  are  the  most  important  grain-growing  areas 
in  Germany  and  Austria.     Belgium  in  normal  times 
is  a  wheat  importer,  but  with  her  territory  violated 
will  have  grown  less  than  usual,  and  will  have  to 
make  a  larger  demand  than  usual  on  the  general 
supply.     Russia,  in  normal  times  a  large  exporter, 
can  now  not  only  have  little  if  any  to  export,  but 
with  the  Dardanelles  at  present  closed  may  be  unable 
to  send  any  supplies  to  the  European  market.     The 
shortage  of  the  European  harvest  is  estimated  by 
Mr.  Fielding  to  be  very  large,  and  the  only  source 
from  which  an  increased  supply  over  the  normal 
can  reasonably  be  expected  is  from  Canada  ;  and  the 
bulk  of  any  Canadian  increase  of  wheat  must  be  at 
the  expense  of  reduction  of  other  crops  in  Canada. 
The  situation  therefore  is  that,  with  the  shortage 
of   European    output    caused    by  the    war,    other 
countries  of  the  world  will  have  to  supply  enor- 
mously increased  quantities. 

To  meet  the  present  deficiency  and  to  make  Great 
Britain  self-supporting  there  is  no  need  to  have 
recourse  to  such  sensational  means  as  the  bringing 
of  Scottish  deer  forests  under  cultivation.  All  that 
would  be  required  would  be  to  reallot  the  uses. to 


ENGLAND'S  FOOD-SUPPLY  17 

which  the  ground  under  cultivation  is  put  at  present, 
to  devote  8,000,000  acres  to  wheat,  16,000,000  acres 
to  general  plough  cultivation,  and  24,000,000  acres 
to  grass.  By  these  means  England  would  be  self- 
supporting  as  regards  her  wheat-supply. 

It  is  not  suggested  that  the  situation  is  an  easy 
one  to  settle.     Many  complex  interdependent  factors 
enter  into  it,  fiscal,  economic,  social  and  practical, 
and  in  times  of  peace  a  great  deal  of  business  and  a 
great  deal  of  thought  would  be  necessary  before  the 
problem  could  be  effectively  approached.     To-day, 
however,  the  country  is  at  war,  and  the  food  problem 
is  only  second  in  urgency  to  that  of  maintaining  our 
armies  at  the  front  and  of  supplying  them  with 
munitions.     A  single  condition  stands  out  with  un- 
mistakable clearness.     The  internal  wheat-supply  of 
Great  Britain  must  immediately  be  very  considerably 
increased.     Abroad  in  times  of  peace  our  neighbours 
have  solved  the  problem  of  feeding  their  own  popu- 
lation by  intensive  cultivation,  but  whereas  both 
France  and  Germany  use  105  pounds  of  artificial 
fertilizers  to  the  acre,  England  makes  use  only  of 
48  pounds  to  the  acre.     The  need  has  now  arisen 
with  exceptional  urgency  to  get  the  utmost  food 
value  possible  out  of  the  soil — wheat  for  the  direct 
consumption  of  man,  pasture  and  other  foodstuffs 
for  the  purposes  of  stock.     And  this  exceptional  need 
has  arisen  at  the  very  moment  when  the  demand 
on  the  world's  stock  of  nitrates  has  attained  a  maxi- 
mum hitherto  undreamt  of.     It  finds  the  British 
soils  at  a  dangerously  low  ebb  in   their  available 
supplies  both  of  phosphates  and  of  nitrates,  and  if 


i8  THE  SPIRIT  OF  THE  SOIL 

large  tracts  of  our  land  are  to  be  laid  down  in  wheat, 
these  must  be  supplied  to  them  at  no  matter  what 
the  cost.  To-day  the  country  is  called  upon  to  face 
at  once  under  the  exceptional  conditions  of  war  the 
very  problem  that  will  have  to  be  faced  in  years  to 
comef  as  a  result  of  natural  developments.  The 
response  made  by  men  of  science,  above  all  by  the 
bacteriologists,  to  the  note  of  warning  in  1898  by 
Sir  William  Crookes  suggests  that  we  may  be  in  a 
position  to-day  to  meet  the  demand  without  un- 
due expenditure. 


CHAPTER  III 

BACTERIA  AND  PROTOZOA 

The  annus  mirabilis — Developments  of  the  modern  era — The 
atom — Electricity — Medicine — Greek  decadence  due  to 
malaria — Extension  of  human  knowledge — Mendel — The 
new  romance — The  role  of  the  earthworm — Bacterial 
empires  in  the  soil — Their  vicissitudes — Their  work — 
Bacteriology  and  astronomy — Properties  of  the  bacterium — 
Advances  in  pathology — The  situation  in  botany — Broad 
generalizations — Work  and  habits  of  the  bacteria — Prepara- 
tion of  farmyard  manure — Carbohydrates  and  proteins — 
Break-up  of  carbon  compounds — Three  groups  to  deal  with 
proteins — Value  of  farmyard  manure  —  Denitrifying  bac- 
teria and  nitrogen  fixers — The  protozoa. 

AN  epitaph  dating  back  to  the  most  glorious  period 
in  Athenian  history  has  set  down  in  terms  of  noble 
simplicity  the  record  of  the  great  Athenians  who 
perished  fighting  for  the  country  on  salients  of 
offence  that  had  been  thrown  out  in  all  directions 
into  Greece  and  into  all  the  barbarian  hinterland. 
The  world,  latinized,  has  since  spoken  of  the  period 
as  the  annus  mirabilis,  and  the  epitaph  sums  up 
grandly  the  stupendous  blaze  of  energy  that  kindled 
the  intelligence  of  the  world,  and  still  acts  to-day  as 
its  most  potent  quickening  force.  It  is  open  to 
question,  however,  whether  the  Greeks  ever  realized 
the  astounding  phenomenon  in  which  they  played 
their  part,  just  as  it  is  open  to  question  to-day 


20  THE  SPIRIT  OF  THE  SOIL 

whether  we  realize  the  unparalleled  developments  of 
the  present  era. 

Contrast  for  a  moment  the  position  of  affairs  as  it 
was  in  1850  and  as  it  is  to-day,  looking  only  along  a 
very  narrow  front.  We  had  learnt  by  long  and 
painful  experiment  that  all  matter  was  composed  of 
elements,  and  Mendeleeff  had  drawn  up  his  famous 
table  showing  that  there  was  some  kinship  between 
the  atoms.  To-day  we  have  made  the  tiny  atom 
almost  visible,  been  able  to  watch  the  spark  that 
its  impact  makes,  traced  out  its  path  as  it  hurls  itself 
through  a  gas,  shattering  the  molecules  that  would 
bar  its  way,  learnt  something  of  the  subtler  matter 
of  which  it  is  composed.  In  electricity  only  the 
broad  foundations  of  the  science  had  been  laid;  the 
telephone  was  not  conceived  of  even  by  the  dreamer ; 
the  telegraph  was  already  doing  pioneer  service  in 
shortening  the  world's  distances;  but  no  man  had 
conceived  of  harnessing  the  ether  and  forcing  it  to 
carry  the  impulses  impressed  on  it  by  the  electric 
spark.  Medicine  was  still  in  an  earlier  era.  Chloro- 
form as  an  anaesthetic  had  barely  been  discovered, 
and  the  surgeon,  ignorant  of  the  nature  of  infection, 
could  not  dare  to  take  advantage  of  more  than  a 
tithe  of  what  it  offered.  Then  came  the  work  of 
Pasteur  and  of  Lister,  bringing  in  its  train  a  flood  of 
knowledge  that  has  swept  away  the  dull  mass  of 
ignorance,  spread  since  the  beginning  of  time  across 
the  path  of  man's  progress.  Had  the  knowledge  of 
to-day  been  available  to  the  Greeks,  there  would  have 
been  no  need  for  the  sudden  eclipse  of  her  civilization. 
It  was  not  her  internal  dissensions  that  destroyed 


BACTERIA  AND  PROTOZOA  21 

her,  but  the  sudden  inroad  of  malaria  that  carried 
off  the  best  of  her  sons,  left  the  race  de-energized, 
and  forced  her  to  hand  on  the  torch  of  civilization 
to  the  victorious  Romans. 

Just  as  the  genius  of  Greece  quickened  into 
activity  the  earlier  of  the  arts  and  sciences,  so  the 
genius  of  modern  Europe  is  to-day  extending  in  all 
directions  the  horizons  of  human  knowledge.  Are 
not  the  biologists  following  out  the  great  principle 
glimpsed  at  by  Mendel,  analyzing  the  factors  of 
heredity,  and  groping  after  the  elucidation  of  one 
of  the  supreme  mysteries  of  the  world  ?  Is  it  not 
true  that  the  experimental  botanist  is  using  a  sure 
method  to  recombine  the  qualities  of  the  plants  and 
evolve  new  species,  as  a  watchmaker  might  take  the 
parts  he  needed  from  a  dozen  watches  and  build  up 
a  new  one  to  suit  his  purpose  ?  Have  we  not  found 
that  the  earth  is  something  more  wonderful  than 
any  thought  her  before  ?  The  Greeks  looked  on  the 
goddess  Gsea  as  the  mother  of  mankind.  In  their 
glorious  mythology  they  pictured  that  men  and 
women  had  broken  into  life  as  the  stones  cast  on  to 
her  touched  her  life-giving  soil.  Countless  legends, 
expressed  in  astonishingly  beautiful  imagery,  have 
told  of  the  sacrament  of  spring,  and  the  Celt  has 
peopled  the  soil  with  gnomes  and  pixies,  friends  or 
enemies  to  man.  Science  working  with  polished 
microscopes,  with  bottled  reagents,  with  curiously 
twisted  retorts,  and  all  the  paraphernalia  of  the 
laboratory,  has  rent  in  twain  the  closely  knit  and 
woven  veil  that  barred  our  access  to  the  mysteries 
of  earth,  and  as  these  are  revealing  themselves  to  us 


22  THE  SPIRIT  OF  THE  SOIL 

the  wonder  of  them  far  transcends  all  that  the 
imagination  of  the  poet  has  conceived.  In  setting 
aside  the  romance  of  the  past  the  laboratory  is 
guiding  us  to  an  astonishingly  greater  romance  of  the 
present.  The  child's  "  Let  us  pretend,"  a  pitiful 
attempt  to  furnish  the  food  that  its  imagination 
demands,  gives  place  to  the  cry  of  "  Let  us  know,'1 
and  in  imaginative  splendour  the  knowledge  of 
to-day  presses  out  beyond  all  that  was  previously 
conceived. 

Who  in  the  past  could  have  imagined  the  mys- 
terious happenings  that  take  place  in  a  small  plot  of 
garden  soil  ?  It  was  a  revelation  to  the  world  when 
Darwin,  lifting  a  corner  of  the  veil,  told  of  the  stu- 
pendously great  part  played  by  the  earthworm  that 
had  been  "  carrying  on  "  unheeded  or  resented  for 
countless  ages  of  time.  But  to-day  we  are  beginning 
to  know  that  the  soil  which  the  gardener  turns  with 
the  spade  is  the  site  of  countless  vast  empires  of 
bacteria.  They  are  empires  that  rise  and  fall  in  the 
short  space  of  weeks,  that  have  great  tasks  to  per- 
form, and  devote  themselves  wholeheartedly  to 
carrying  them  out,  empires  liable  to  countless  vicissi- 
tudes. Now  they  are  overwhelmed  by  the  vast 
immigrations  that  come  to  them  suddenly  as  gar- 
dener or  husbandman  pours  into  their  borders 
countless  myriads  of  individuals  with  each  spadeful 
of  his  manure.  Periods  of  drought  wreak  havoc  on 
their  colonies,  the  lives  of  whole  empires  being 
dependent  on  the  chances  of  the  climate.  They  are 
preyed  on  by  monstrous  protozoa  that  may  exact 
a  greater  toll  than  even  they  with  their  astounding 


BACTERIA  AND  PROTOZOA  23 

fertility  can  cope  with.  Or  they  may  perish  through 
their  own  activity,  their  life  clogged  by  the  products 
they  have  themselves  formed.  Widely  they  differ 
among  themselves.  Some  of  them  build  up,  others 
of  them  destroy ;  even  in  the  same  species  there  are 
vast  differences.  Like  communities  of  men  and  like 
single  individuals,  there  are  some  that  are  energetic, 
others  that  are  lazy,  others  that  are  tired;  as  food 
fails,  or  is  abundant,  they  are  poorly  fed  or  well 
nourished.  They  are  healthy  or  sick.  To  a  bad 
environment  or  a  good  one  they  respond  as  readily 
and  as  notably  as  the  people  in  our  great  cities,  and 
with  them,  too,  their  heredity  has  a  dominating 
influence. 

Only  within  recent  years  have  we  realized  how  in- 
timately our  prosperity  is  dependent  on  the  bacterial 
population  of  the  soil.  Without  bacterial  activity 
it  would  be  of  no  avail  to  the  farmer  to  dung  his 
crops;  it  would  be  useless  for  him  to  attempt  to 
enrich  his  soil  by  ploughing  in  green  stuff.  The 
plants  and  trees  that  have  lived  and  died  wresting 
Carbon  from  the  air  would  only  cumber  the  land. 
All  vegetation  would  be  choked,  and  the  earth  would 
become  a  vast  wilderness,  unbeautiful  and  silent, 
save  for  the  winds  and  seas  and  other  manifestations 
of  lifeless  forces. 

Though  at  present  we  are  only  groping  as  pioneer 
discoverers  in  a  new  universe,  there  are  some  great 
features  that  we  are  able  plainly  to  recognize,  dimly, 
it  may  be,  as  astronomers  who  map  the  surface  of 
the  moon.  As  the  astronomers  can  speak  with 
certainty  of  the  mountains  of  the  moon,  of  the  con- 


24  THE  SPIRIT  OF  THE  SOIL 

ditions  of  its  atmosphere,  of  the  laws  governing  its 
movement  through  space,  so  there  are  many  proper- 
ties of  the  bacterium  on  which  it  is  safe  to  dogmatize. 
We  know  that  the  bacterium  is  an  organism  low  in 
the  vital  scale,  consisting  of  a  single  cell,  the  proto- 
plasm or  vital  unorganized  portion  of  which  is  sur- 
rounded by  a  cell  membrane  which  may  consist  of 
cellulose,  but  which  more  often  is  made  up  of  a  horn- 
like substance.     We  are  on  sure  ground  when  we 
state  that  it  usually  reproduces  its  kind  by  forming 
a  partition  in  the  middle  of  its  substance  and  dividing 
into  two.     Observation  has  taught  us  that  the  time 
taken  for  division  is  in  favourable  conditions  about 
half  an  hour.     It  is  certain  that  in  the  vast  kingdom 
of  the  bacteria  there  are  only  a  few  that  are  able  to 
give  rise  to  diseases  in  man  and  animals.     Most  of 
these  have  certain  characteristics  that  enable  them 
to  be  certainly  identified  and  incriminated  by  the 
bacteriologist.     The  pathologist  has  gone  farther, 
and  is  getting  an  insight  into  the  means  by  which 
the  body  is  able  to  repel  the  attacks  by  which  it 
is   constantly   threatened.     He   talks   learnedly   of 
opsonins,  antibodies,  and  the  like,  and  his  know- 
ledge at  any  rate  is  sufficiently  precise  and  accurate 
to  enable  him  to  build  up  on  it  a  rational  system 
of  treatment  for  the  individual  struck  down  by  a 
disease. 

While  the  bacteriologist  who  has  directed  his 
attention  to  the  bacteria  connected  with  the  causa- 
tion of  disease  stands  on  a  firm  foundation  of  proved 
and  demonstrated  fact,  and  may  compare  his  results 
with  those  with  which  the  astronomer  deals  in 


BACTERIA  AND  PROTOZOA  25 

mapping  the  moon,  and  in  computing  her  orbit,  the 
position  of  the  bacteriologist  who  is  grappling  with 
botanical  and  agricultural  problems  is  far  less 
enviable.  He  must  be  compared  rather  with  the 
men  who  are  making  a  study  of  Mars.  There  are 
certain  broad  facts  of  which  he  can  speak  with 
certainty,  but  as  regards  others  he  is  beset  with 
controversy,  struggling  as  it  were  to  put  a  correct 
interpretation  on  the  vague  markings  that  he  speaks 
of  provisionally  as  the  canal  system  of  Mars.  There 
is  no  dispute  now  as  to  the  prominent  part  that 
bacteria  play  in  relation  to  soil  fertility.  It  is  a 
commonplace  that  in  an  ounce  of  rich  loam  soil  there 
may  be  as  many  as  150,000,000  bacteria,  while  in 
ground  polluted  with  sewage  the  number  may  reach 
the  fantastic  total  of  3,000,000,000.  Much,  too,  of 
the  work  that  the  bacteria  accomplish  and  of  their 
habits  is  known,  proved  and  accepted.  Warmth 
and  a  moderate  amount  of  moisture  promote  their 
growth;  cold  and  excessive  moisture  or  excessive 
drought  arrest  their  development.  There  are  some 
that  can  thrive  in  the  presence  of  air,  others  that  can 
only  do  their  work  if  air  is  rigidly  excluded.  The 
function  of  some  of  them  is  to  break  down  complex 
substances  to  simpler  bodies  or  even  to  elements; 
the  function  of  others  is  to  build  up  substances  of 
high  potential  energy  from  inert  constituents.  With- 
out their  activity  the  world  would  rapidly  arrive  at 
a  deadlock.  The  material  of  plants  and  animals  that 
had  reached  and  passed  their  prime  would  cumber 
the  ground,  and  the  fabric  of  their  tissues  would 
not,  as  now,  become  available  as  the  raw  substances 


26  THE  SPIRIT  OF  THE  SOIL 

from  which  other  plants  and  animals  can  build  up 
their  tissues. 

Such  are  some  of  the  broad  generalizations  that 
constitute  the  foundations  on  which  the  plant 
bacteriologist  is  called  upon  to  build,  and  already 
from  them  he  has  been  able  to  formulate  other 
narrower  generalizations  that  are  of  vital  importance 
to  the  art  of  agriculture.  We  shall  see  more  of  them 
in  later  chapters,  but  it  may  be  helpful  at  this  stage 
barely  to  outline  the  chief  points  on  which,  as  we 
know  it  at  present,  the  question  of  soil  fertility  from 
the  bacterial  standpoint  mainly  depends.  One  may 
accept  it  as  broadly  true  that  we  know  the  con- 
ditions of  soil  fertility  if  we  are  able  to  trace  the 
processes  by  which  a  load  of  farmyard  manure 
becomes  available  as  plant  food. 

When  the  manure  is  thrown  freshly  on  to  the  heap 
it  consists  essentially  of  a  heterogeneous  mass  of 
material,  loaded  up  with  bacteria,  and  containing  a 
great  variety  of  Carbon  compounds,  with  traces  of 
Phosphates,  Potash,  and  so  forth.  It  is  with  the 
Carbon  compounds  that  we  are  concerned.  These 
fall  into  two  great  classes — that  in  which  the  Carbon 
is  combined  with  various  quantities  of  Hydrogen 
and  Oxygen,  and  that  in  which  Nitrogen  is  also  one 
of  the  constituents  (the  proteins).  As  they  are 
found  in  fresh  manure  neither  class  is  available  as  a 
plant  food.  Common  farmyard  experience  tells  us 
that  the  manure-heap  heats  and  shrinks,  and  it  needs 
no  great  effort  of  imagination  to  realize  that  a  process 
is  at  work  comparable  with  what  occurs  when  a  bon- 
fire is  being  burnt.  And  this  is  actually  what  is 


BACTERIA  AND  PROTOZOA       27 

taking  place ;  but  whereas  in  the  bonfire  a  tempera- 
ture is  reached  at  which  the  oxygen  of  the  air  is  able 
directly  to  combine  with  the  Carbon  compounds  and 
break  them  down  into  Carbon  dioxide  and  Water,  in 
the  manure-heap  a  similar  but  slower  and  less  com- 
plete process  is  occurring.  This  change  is  the 
earliest  to  be  noticed,  and  though  other  changes  are 
happening  at  the  same  time,  they  are  more  logically 
considered  as  being  later.  In  the  first  instance  the 
bacteria — there  are  varieties  that  can  do  the  work 
in  the  presence  of  air  if  the  heap  is  loosely  com- 
pacted, and  varieties  that  can  accomplish  it  if  all 
air  is  excluded — break  down  the  complex  Carbon 
compounds,  turning  them  into  simpler  bodies,  and 
partly  into  Carbon  dioxide  that  escapes  into  the  air. 
These  nations  of  bacteria  wax  and  wane,  giving  place 
to  three  separate  groups  that  one  after  another  deal 
with  the  nitrogen  compounds.  The  bacteria  called 
upon  to  deal  with  these  bodies  have  to  be  fed  with 
readily  assimilable  carbon  compounds.  The  first 
group,  some  of  whose  members  can  work  with  air 
and  others  without,  seize  on  the  nitrogen  fixed  in 
complex  groupings  and  split  off  ammonia  from  the 
protein  (NH3).  Their  finished  product  they  hand 
on  to  another  group.  These  can  only  work  in  the 
presence  of  air,  and  they  require  lime  or  some  basic 
material  to  absorb  the  acid  they  produce.  Under 
their  influence  the  ammonia  they  have  had  passed 
to  them  as  the  raw  material  (often  in  the  form  of 
Ammonium  Sulphate  [(NH4)2SO4])  is  changed  into 
nitrite  (NO2),  and  this  by  a  third  group,  also  acting 
in  the  air,  and  in  the  presence  of  a  base  becomes 


28  THE  SPIRIT  OF  THE  SOIL 

nitrate  (N03),  which  will  be  found  in  the  heap  in 
some  such  soluble  form  as  Calcium  Nitrate 
[Ofc(N08)J. 

Apart  from  the  value  of  its  mechanical  structure, 
and  apart  from  the  Phosphates  and  Potash  that  it 
contains,  the  essential  value  of  farmyard  manure  to 
the  land  is  that  it  possesses  sufficient  carbon  com- 
pounds in  assimilable  form  to  act  as  a  food-supply 
for  the  bacteria,  and  that  it  contains  a  large  supply 
of  the  nitrogenous  food  material  essential  for  plant 
nourishment. 

This  is  not  the  whole  story,  however.  The  bac- 
teria of  which  I  have  so  far  spoken  are  the  fairy  god- 
mothers of  the  romance — the  fairy  super-godmother 
has  not  yet  appeared  on  the  stage — but  the  romance 
itself  would  be  incomplete  if  there  were  no  hard- 
featured,  cross-grained  witch.  Experience  has  long 
taught  that  the  loosely  piled  heap  will  burn  away 
to  waste  if  it  is  too  loosely  stored  owing  to  the  exces- 
sive amount  of  oxygen  supplied  to  the  first  group  of 
bacteria.  In  agriculture,  as  in  politics,  the  advice  of 
Talleyrand  especially  as  regards  bacteria  surtout  pas 
trop  de  zele  is  eminently  sound,  but  however  carefully 
he  goes  to  work,  the  farmer  may  find  that  the  cross- 
grained  witch  has  come  uninvited  to  the  feast  in  the 
shape  of  a  denitrifying  bacterium  that  seizes  on  the 
precious  nitrates  designed  as  plant  food,  and  waste- 
fully  turns  them  into  the  nitrogen  that  is  useless  for 
plants,  and  escapes  inert  into  the  open  air. 

It  is  the  super-godmother,  however,  that  comes  to 
the  rescue.  A  group  of  bacteria  exists;  the  name 
of  one  of  the  group  is  Azotobacter,  and  it  has  the 


BACTERIA  AND  PROTOZOA  29 

power  of  starting  with  the  inert  nitrogen  of  the  soil 
air  and  of  changing  it  into  nitrogenous  plant  food. 
The  rotted  manure  gives  it  the  food  of  which  -it 
stands  in  need,  and  under  favourable  conditions  it 
is  able  to  go  on  steadily  adding  to  the  store  of  nitrog- 
enous food  material  in  the  soil. 

Such  in  crudest  outline  is  the  function  of  the  soil 
bacteria  and  the  way  in  which  they  lead  to  an 
increase  in  soil  fertility.  In  the  chapters  immedi- 
ately following  I  shall  endeavour  to  describe  their 
work  in  greater  detail,  and  to  show  how  it  is  possible 
for  man  successfully  to  co-operate  with  them.  A 
word,  however,  in  conclusion  of  this  chapter  must 
be  written  of  the  protozoa,  for  though  they  are  not 
concerned  with  the  general  argument  of  this  book, 
they  bear  an  important  relation  to  the  soil  bacteria 
and  seriously  affect  their  welfare. 

The  protozoon  is  not  a  bacterium,  but  a  minute 
animal  requiring  the  magnification  of  a  strong  micro- 
scope lens  to  be  seen.  Small  though  he  is,  he  is  as 
terrible  and  monstrous  a  foe  to  the  bacteria  as  the 
vast  swamp  monsters  must  have  proved  to  emerging 
man  in  the  Eocene  times.  Looked  at  in  water  under 
the  microscope  he  is  seen  creating  in  the  medium 
whirlpools  against  which  the  hapless  bacteria  are 
powerless  to  contend,  and  drawing  them  defenceless 
into  his  body.  Recent  experiments  at  Rothamsted 
have  shown  that  these  animalculae  in  certain  con- 
ditions may  seriously  check  the  bacteria  of  the  soil, 
and  may  gravely  affect  the  health  of  plants,  especially 
in  rich,  ^  highly-manured  soil.  Experimentally  in 
horticulture  it  has  proved  practicable  to  get  rid  of 


30  THE  SPIRIT  OF  THE  SOIL 

them  by  chloroform  and  other  similar  means,  and  it 
seems  as  if  the  burning  of  cultivated  soil  by  the 
Indians,  a  practice  dating  back  to  traditional  periods 
of  Indian  agriculture,  may  have  had  as  one  of  its 
benefits  the  destruction  of  the  protozoa  of  the  soil.* 
Fortunately  they  are  less  resistant  than  the  bacteria, 
and  when  these  stringent  methods  are  employed  all 
the  protozoa  perish,  while  a  considerable  number  of 
the  bacteria  are  left,  and  these,  rid  of  the  protozoan 
enemies,  are  able  to  jump  into  an  amazingly  rapid 
development  and  continue  their  work  of  securing  a 
suitable  soil  environment  for  the  plants.  It  is, 
however,  only  in  excessively  manured  soils  that  they 
constitute  a  serious  problem,  and  this  short  account 
given  of  them  may  therefore  suffice. 

*  Cf.  Virgil,  Georgics : 

"  Often  you  will  find  it  well  to  burn 
The  garnered  field  and  set  the  flimsy  straw 
A-cackling  in  the  flames.     Whether  perchance 
The  land  in  this  wise  finds  some  unknown  force, 
Some  fat  enrichment ;  or  that  every  fault 
Thereby  is  purified  by  fire,  and  all 
The  useless  humours  purged ;  or  that  the  heat 
By  its  own  virtue  loosens  secret  pores 
And  paths  unseen  whereby  the  sap  may  flow 
To  the  young  grasses." 


CHAPTER  IV 

PEAT  AND  ITS  USES 

Early  investigations  of  the  Royal  Society — Continuity  of  mental 
processes — Reality  of  material  progress — Diamonds  and 
peat:  an  analogy — Conditions  of  peat  deposition — Its  con- 
stitution— Variations  in  composition — Mineral  and  organic 
residues — Peat  formation — Peat,  lignite,  and  coal — Extent 
of  peat  deposits — Uses  of  peat — Fuel — Power — Chemical 
products  —  Paper  —  Artificial  wood  mattresses —  Surgical 
dressings — Litter — Dr.  Dachnowski's  views — Objections  to 
peat  as  manure  —  Experiments  with  peat-moss  litter  at 
Kew  Gardens — Deleterious  effects — Dr.  Voelcker's  explana- 
tion— Contrast  with  humogen. 

IF  those  who  affect  to  consider  that  there  has  been 
no  advance  in  the  world's  knowledge  during  the  last 
quarter  millennium  would  study  the  early  history  of 
the  Royal  Society,  founded  a  little  more  than  250 
years  ago,  they  would  be  amazed  chiefly  by  two 
points.  The  first  would  be  the  completeness  with 
which  the  founders  and  early  Fellows  of  the  Society 
adopted  the  methods  of  observation  and  experiment, 
reasoning  according  to  completely  modern  methods 
of  thought,  and  the  second  the  appalling  extent  of 
ignorance  that  prevailed  among  those  who  were  the 
best  instructed  and  most  enlightened  of  their  time. 
Men  steeped  in  literary  lines  of  thought  are  fre- 
quently pleased  to  quote  with  smug  expressions  of 

31 


32  THE  SPIRIT  OF  THE  SOIL 

approval  the  old  French  saw,  Plus  ca  change,  plus 
c'est  la  meme  chose,  and  affect  an  almost  personal 
triumph  when  they  are  able  to  show  that  the  passions 
and  mental  processes  in  man  to-day  are  strictly  com- 
parable with  those  prevailing  in  the  earliest  historic 
times.  They  seem  to  believe  that  in  emphasizing 
the  fact  that  the  various  races  of  men  are  fixed  types, 
variable  only  within  the  limits  of  a  fixed  type, 
they  are  confuting  the  idea  of  there  being  any  possi- 
bility of  progress.  In  doing  so  they  belittle  and 
deny  the  value  of  the  material  advances  made, 
blinding  themselves  to  the  real  facts  of  progress. 

When  one  cares  to  go  back  to  the  original  records, 
however,  the  reality  of  this  material  progress  is 
strikingly  brought  out.  In  turning  over  at  random 
notices  of  the  early  investigations  made  by  the 
Fellows  of  the  Royal  Society,  one  comes  across  such 
records  as  the  following : 

"  March  25,  1661. — Mr.  Boyle  was  desir'd  to  bring 
in  the  name  of  the  place  in  Brasil  where  that  wood 
is  that  attracts  fishes ;  and  also  of  the  fish  that  turns 
to  the  wind  when  suspended  by  a  thread/' 

"  May  8. — Dr.  Clarke  was  intreated  to  lay  before 
the  Society  Mr.  Pellin's  relation  of  the  production  of 
young  vipers  from  the  powder  of  the  liver  and  lungs 
of  vipers." 

"  June  5. — Col.  Tuke  related  the  manner  of  the 
rain  like  corn  at  Norwich,  and  Mr.  Boyle  and  Mr. 
Evelyn  were  intreated  to  sow  some  of  those  rained 
seeds  to  try  their  product/' 

"  June  26. — Sir  G.  Talbot  brought  in  his  experi- 
ments of  sympathetick  cures/'* 

*  The  following  extract  from  this  paper  may  be  of  interest : 
"  An  English  mariner  was  wounded  at  Venice  in  four  severall 


PEAT  AND  ITS  USES  33 

"  July  10. — The  fresh  hazell  sticks  were  produced, 
wherewith  the  divining  experiment  was  tried  and 
found  faulty. 

"  September  4. — Sir  K.  Digby  brought  in  a  letter 
from  a  friend  of  his  in  Florence,  written  in  1656, 
which  treats  of  a  petrified  city  and  inhabitants."* 

Instances  of  this  sort  could  be  quoted  almost 
indefinitely  to  show  the  extent  of  the  prevailing 
ignorance  of  natural  phenomena,  and  a  great  debt 
of  gratitude  is  owed  to  the  Royal  Society  even  in 
those  early  days  for  their  fearless  investigations.  A 
source  that  they  used  largely  for  extending  their 
knowledge  was  to  make  inquiries  of  sea  captains  and 
of  residents  in  foreign  countries  to  confirm  or  refute 
the  astonishing  stories  that  were  brought  from 
abroad  to  this  country.  Sprat,  in  his  History  of  the 
Royal  Society,  prints  a  long  list  of  the  questions 
addressed  by  the  Society  in  its  early  days  to  Sir 
Philiberto  Vernatti,  resident  in  Batavia,  and  of  his 
answers.  The  first  of  the  questions  is : 

places  soe  mortally,  that  the  murderer  took  sanctuary,  the 
wounded  bled  three  days  without  intermission ;  fell  into  frequent 
convulsions  and  swounings;  the  chirurgeons  despayring  of  his 
recovery,  forsook  him.  His  comrade  came  to  me,  and  desired 
me  to  demand  justice  from  the  Duke  upon  the  murderer  (as  sup- 
posing him  already  dead) ;  I  sent  for  his  bloud  and  dress'd  it, 
and  bad  his  comrade  haste  back  and  swathe  up  his  wounds  with 
cleane  linen.  He  lay  a  mile  distant  from  my  house,  yet  before 
he  could  gett  to  him,  all  his  wounds  were  closed,  and  he  began 
visibly  to  be  comforted.  The  second  day  the  mariner  came  to 
me,  and  told  me  his  friend  was  perfectly  well,  but  his  spirits  soe 
exhausted  he  durst  not  adventure  soe  long  a  walke.  The  third 
day  the  patient  came  himself  to  give  me  thanks,  but  appeared 
like  a  ghost;  noe  bloud  left  in  his  body." 
*  Weld,  History  of  the  Royal  Society. 

3 


34  THE  SPIRIT  OF  THE  SOIL 

"  Q.  i.  Whether  Diamonds  and  other  Precious 
Stones  grow  again  after  three  or  four  years,  in  the 
same  places  where  they  have  been  digged  out  ? 

"A.  Never,  or  at  least  as  the  memory  of  man  can 
attain  to." 

When  one  turns  from  the  ancient  records  of  the 
Royal  Society  to  a  book  published  so  recently  as 
1912  on  the  Peat  Deposits  of  Ohio,  by  Dr.  Alfred 
Dachnowski,  it  comes  as  a  surprise  to  read  the  fol- 
lowing remark  almost  at  the  opening  of  his  first 
chapter : 

"  Exact  and  systematic  study  of  peat  began  in 
Europe  in  1750,  when  various  scientific  societies 
offered  prizes  for  memoirs  on  the  origin,  formation, 
and  nature  of  peat.  Then,  as  to-day,  some  persons 
held  that  peat  bogs  were  useless  obstacles  to  com- 
merce and  agriculture;  were  places  of  malarious 
fevers  and  the  causes  of  spring  frosts;  while  others 
advanced  the  idea  that  peat,  if  once  dug  out,  would  grow 
again  spontaneously ." 

This  quotation  is,  I  think,  memorable  in  showing 
how  greatly  the  oldest  of  the  sciences,  agriculture, 
in  certain  of  its  aspects  at  any  rate,  lagged  behind  at 
a  time  when  the  modern  world  had  begun  to  show 
an  active,  intelligent,  scientific  curiosity  into  the 
causes  of  all  sorts  of  natural  phenomena. 

The  general  conditions  under  which  the  deposits 
of  peat  were  laid  down  are  to-day  thoroughly  well 
understood  from  the  general  standpoint,  though  a 
vast  amount  of  work  remains  to  be  done  before  the 
various  problems  connected  with  peat  formation 
can  be  regarded  as  solved.  As  with  most  natural 
substances  peat  is  the  name  given  to  a  class  of 


PEAT  AND  ITS  USES  35 

products,  and  the  term  no  more  describes  a  definite 
unit  compound  or  mixture  than  does  the  term  "  coal" 
in  the  mineral  kingdom,  or  the  terms  "horse," 
"  dog,"  "  man,"  or  what  not  in  the  animal  kingdom. 
As  will  be  seen  in  the  later  pages  of  the  book,  it 
would  not  be  possible  for  the  makers  of  bacterized 
peat  to  copy  the  immortal  recipe  of  Mrs.  Beeton, 
beginning,  "  Take  a  hare,"  and  to  start  off  an  account 
of  their  manufacturing  process  with  the  words, 
"  Take  a  ton  of  peat."  The  exact  character  of  any 
peat  that  is  to  be  used  has  carefully  to  be  studied 
and  tested  to  discover  whether  or  not  it  will  give 
satisfactory  results  when  converted  into  humogen. 

Generally  one  may  describe  peat  as  disintegrating 
vegetable  matter.  It  may  be  coarsely  fibrous  and 
matted,  and  contain  plainly  recognizable  in  its  sub- 
stance the  roots,  rhizomes,  and  aerial  parts  of  plants. 
Or  it  may  be  highly  compact;  the  fibrous  con- 
stituents of  it  may  have  already  decomposed  and  the 
great  portion  of  it  may  consist  of  disintegrating 
leaves  and  woody  parts  of  trees  and  shrubs.  These 
may  be  regarded  roughly  as  the  limiting  substances 
in  one  direction,  and  the  other  of  the  various  agglo- 
merations that  may  be  described  as  peat ;  but  both 
in  chemical  and  mechanical  properties  there  are 
enormous  differences.  One  has  only  to  consider  the 
conditions  in  which  the  peat  has  been  laid  down  to 
realize  that  this  is  inevitable.  Imagine  the  vastly 
differing  matter  that  is  waterborne  by  various 
streams  to  be  deposited  in  the  rankly  growing  vege- 
tation of  the  forming  peat  bog.  Bear  in  mind  the 
dust  carried  by  the  air,  much  of  which  has  inevitably 


36  THE  SPIRIT  OF  THE  SOIL 

been  trapped  on  the  leaves  of  the  growing  plants. 
Consider  the  differences  in  the  animal  organisms, 
crustaceae,  and  so  forth,  that  have  lived  and  died 
during  the  long  periods  of  geological  time,  and  there 
will  be  little  trouble  in  recognizing  that  in  mineral 
content  one  peat  bog  will  differ  widely  from  another. 

This  variation  in  life  is  a  factor  that  has  constantly 
to  be  borne  in  mind  when  dealing  with  peat,  and  the 
plants  of  which  it  is  composed.  Pond,  lake,  bog, 
forest,  and  swamp,  have  well-defined  differences  in 
the  vegetation  that  grows  on  them,  and  the  plants 
growing  in  each  will  vary  with  changing  conditions 
of  soil,  climate,  and  general  environment.  The  juicy 
character  of  water-plants  is  perpetuated  in  the  peat 
they  form  by  a  soft  structureless  material.  When 
sedges  and  grasses  predominate,  the  peat,  as  one 
would  expect,  tends  to  be  fibrous  and  of  the  nature  of 
turf.  From  trees  and  shrubs  is  derived  a  woody 
type  of  peat. 

To  those  not  professionally  concerned  with  the 
problem  it  is  often  somewhat  of  a  puzzle  to  say  why 
in  certain  cases  coal  is  formed  as  the  result  of  the 
decay  of  vegetable  matter,  while  in  other  cases  peat 
results.  Peat  must  be  regarded  as  the  result  of  the 
first  of  the  great  changes  undergone  by  organic  matter 
on  its  way  to  become  coal.  What  has  occurred  is 
that  plant  debris  has  accumulated  in  a  relatively 
permanent  body  of  water  or  in  moist  shallow  places. 
Weathering  processes  set  in  as  soon  as  the  tissues  are 
lifeless,  promoted  and  aided  throughout  by  the  action 
of  fungi  and  bacteria.  The  products  of  decay  accu- 
mulate beneath  the  surface  of  the  water,  and  in  the 


PEAT  AND  ITS  USES  37 

absence  of  air  the  bacterial  activity  is  checked,  and 
complete  resolution  of  the  plant  debris  to  its  simplest 
constituents  is  arrested.  In  the  process  some  of 
the  carbon  has  disappeared  in  the  form  of  carbon 
dioxide  or  marsh  gas,  while  much  has  been  left  behind 
in  the  form  of  humic  acid  and  other  relatively  com- 
plex products,  the  composition  of  the  mixture 
depending  on  the  original  constituents  of  the  moss, 
on  the  bacteria  and  fungi  that  have  acted  on  it,  and  on 
the  atmospheric  and  other  conditions  in  which  they 
have  done  their  work.  The  latest  materials  to  be 
altered  are  the  woody  plant  tissues,  but  as  the  peaty 
deposit  gets  covered  and  subjected  to  pressure  as  a 
result,  for  instance,  of  the  slow  local  sinking  of  the 
earth's  crust,  atmospheric  air  becomes  completely 
excluded,  fermentation  sets  in,  the  oxygen  combined 
with  the  tissues  tends  more  and  more  to  disappear, 
and  the  moss  then  goes  through  the  changes,  be- 
coming first  peat,  then,  under  the  influence  of  time 
pressure,  and  further  bacterial  action,  lignite,  and, 
lastly,  as  the  pressure  further  increases,  coal.  So 
much  at  the  present  stage  for  the  composition  of 
peat,  a  subject  to  which  I  shall  have  to  return  in  the 
chapter  on  the  humus  of  the  soil. 

That  the  problem  of  the  utilization  of  peat  is  an 
important  one  to  the  world  is  shown  conspicuously 
by  a  glance  at  the  extent  of  the  deposits  present  in 
various  parts  of  the  world.  In  Europe  there  are 
believed  to  be  212,700  square  miles  of  bog ;  in  Canada 
50,000  square  miles;  in  the  United  States  of  America 
35,000  square  miles;  in  European  and  Asiatic  Russia 
70,000  square  miles.  Northern  Europe  alone  is  esti- 


38  THE  SPIRIT  OF  THE  SOIL 

mated  to  consume  annually  about  10,000,000  tons 
of  peat,  while  each  year  Russia  produces  4,000,000 
tons,  Germany  2,000,000  tons,  and  Holland  and 
Sweden  each  1,000,000  tons. 

These  may  seem  brave  figures,  but  despite  them 
peat  is  a  world  product  little  in  demand.  Many  men 
have  tried  to  utilize  it  for  various  purposes.  Great 
works  have  time  and  again  been  set  up  by  the  side 
of  peat  bogs ;  there  has  been  abundant  activity  and 
enthusiasm,  but  the  wheels  of  the  machinery  have 
slackened  more  often  than  not  and  stopped,  and  the 
attempt  to  utilize  peat  has  in  the  majority  of  cases 
been  written  down  a  failure.  The  fact  is  the  more 
curious  when  one  knows  the  many  uses  to  which 
peat  may  be  put,  and,  under  certain  conditions,  has 
been  put  successfully.  As  in  humogen  it  is  probable 
that  there  will  be  a  considerable  demand  for  the  raw 
material,  it  will  perhaps  be  of  interest  to  consider 
some  of  the  present  uses  against  which  this  new  use 
will  have  to  come  into  competition. 

The  use  of  peat  as  a  fuel  in  the  districts  from  which 
it  is  cut  goes  back  to  the  earliest  times.  In  the 
minds  of  English  readers  it  is  associated  chiefly  with 
Ireland,  and  the  peat  fire,  like  the  jaunting-car,  is 
the  novelty  that  impresses  itself  most  obviously  on 
the  mind  of  the  tourist  as  a  feature  of  the  typically 
Irish  environment.  In  Ireland  peat  really  does 
enter  into  the  life  of  the  people.  It  has  given  the 
peculiar  acrid  taste  of  its  smoke  to  the  whisky  of  the 
country;  it  is  burnt  in  the  tumbledown  cottages 
scattered  far  away  from  civilization ;  and  when  the 
tourist  wishes  to  carry  away  with  him  a  memento  of 


PEAT  AND  ITS  USES  39 

his  visit  to  Ireland,  he  usually  does  so  by  buying  a 
trinket  carved  out  of  the  black  bog  oak  that  has  been 
lying  for  centuries  preserved  from  the  decaying 
influences  of  climate  beneath  the  covering  of  peat. 

While  peat  is  used  in  this  crudely  simple  way  as  a 
fuel  in  Ireland  and  elsewhere,  there  have  been  many 
attempts  made  to  employ  it  on  a  larger  scale.  One 
reads  of  press  peat,  pressed  peat,  condensed  peat, 
machine -formed  peat,  wet-process  peat,  briquetted 
peat,  all  of  which  represent  the  attempts  of  the 
inventor  to  spread  the  utilization  of  peat  as  a  fuel 
over  areas  remote  from  the  peat  bog,  but  their  efforts 
have  met  with  little  success.  Peat  has  a  low  heating 
value ;  special  grates  are  required  for  its  consumption, 
and  the  relatively  large  quantity  of  ash  makes  the 
handling  of  it  a  difficult  matter.  The  experiment 
has  even  been  made  of  powdering  the  peat  and 
employing  it  in  special  powder  burners,  and  it  seems 
that  it  is  only  because  of  the  low  price  of  coal  that  in 
this  form  it  has  not  become  really  popular.  The 
process  of  briquetting  peat  again  is  one  that  has 
given  good  prospects  of  success.  To  prepare  the 
briquette  the  raw  peat  is  treated  and  pressed.  As  a 
result  of  the  treatment  a  black  heavy  compact  sub- 
stance results  that  is  pleasant  to  handle,  and  that 
has  a  fuel  value  comparable  with  that  of  ordinary 
bituminous  coal.  The  fact  remains,  however,  that 
so  far  the  briquettes  have  not  come  into  public 
favour.  In  peat  coke  one  meets  with  another  of 
the  attempts  made  to  establish  peat  as  a  common 
household  fuel.  On  paper  the  scheme  seems  promis- 
ing enough.  By-products  similar  to  those  obtained 


40  THE  SPIRIT  OF  THE  SOIL 

from  coal  are  obtained,  and  the  coke  itself  forms  a 
satisfactory  fuel,  which  in  several  ways  is  superior  to 
charcoal ;  but  the  fact  has  to  be  faced  that  the  manu- 
factory producing  it  that  seemed  the  most  flourishing 
has  been  forced  to  suspend  manufacture  because  the 
cost  of  preparing  the  coke  was  too  high  to  make  the 
venture  practicable. 

Frequently  the  suggestion  has  been  made  that  it 
should  be  practicable  to  utilize  the  peat  on  the  spot 
as  a  source  of  power,  and  in  Germany  and  Sweden 
particularly  several  plants  have  been  equipped  for 
the  purpose.  Excellent  illuminating  gas  can  be 
obtained  by  heating  the  peat  in  retorts,  and  the 
material  is  also  suitable  for  making  water-gas,  fuel- 
gas,  and  producer  gas.  There  are  several  plants  on 
the  market  designed  for  the  manufacture  of  the  gas 
in  one  or  other  of  these  forms,  and  the  peat  bogs  in 
Germany  and  Sweden  have  been  made  use  of  to  a 
considerable  extent  in  metallurgical  operations,  in 
brick  and  glass  making,  and  in  lime  burning. 

Unquestionably  peat  as  a  fuel  has  a  future  before 
it ;  the  trouble  at  present,  however,  is  that  the  price 
of  coal  is  so  low  that  it  is  difficult  for  other  sources 
of  power  to  compete  against  it,  a  fact  that  is  perhaps 
most  emphatically  brought  out  when  one  considers 
that  it  is  found  to  be  less  expensive  to  pump  the 
marsh  waters  off  the  land  in  such  places  as  Norfolk 
by  coal-using  steam-engines  than  it  is  to  utilize 
windmills  for  the  purpose. 

The  utilization  of  peat  as  a  source  of  chemical 
products  has  attracted  a  considerable  amount  of 
attention  in  recent  years.  There  are  processes  by 


PEAT  AND  ITS  USES  41 

which  alcohol  can  be  derived  from  peat  by  means  of 
fermentation,  and  large  experimental  plants  have 
been  equipped  and  run  for  the  purpose;  but  here 
again  it  has  usually  been  found  that  the  returns  do 
not  allow  a  sufficient  profit  for  the  manufacture  to 
be  successfully  carried  on.  Both  nitrate  and  ammo- 
nium sulphate  have  been  derived  from  peat,  and  in 
the  latter  case  particularly  the  claims  of  inventors 
seem  to  suggest  that  the  peat  might  form  the  basis 
of  a  profitable  industry.  Here,  too,  however,  it  is 
only  possible  to  say  that  the  process  is  in  the  experi- 
mental stage,  and  that  hitherto  it  has  been  of 
theoretical  rather  than  practical  interest. 

Paper  is  another  substance  that  can  be  derived 
from  certain  varieties  of  peat,  but  the  product  is  dark 
in  colour,  and  only  suitable  for  cardboard  or  coarse 
brown  papers.  In  this  instance,  as  in  so  many 
others,  the  manufacture  has  not  gone  beyond  the 
experimental  stage  owing  to  the  expense  of  reducing 
the  peat  fibre  to  a  condition  suitable  for  use.  The 
same  may  be  said  of  the  attempts  to  utilize  peat  for 
woven  fabrics,  and  to  form  out  of  it  a  sort  of  artificial 
wood. 

To  many  it  may  come  as  a  surprise  to  hear  that 
peat  possesses  absorbent,  deodorizing,  and  anti- 
septic properties,  and  in  several  tentative  ways 
attempts  have  been  made  to  exploit  them.  Mat- 
tresses made  of  peat  have  been  constructed  for 
hospital  use,  and  they  have  the  advantage  of  being 
light,  resilient,  soft,  inodorous,  and  very  cheap. 
Further,  American  surgeons  have  made  use  of  peat 
purified  and  powdered  for  dressing  cuts,  burns,  and 


42  THE  SPIRIT  OF  THE  SOIL 

other  wounds,  with  excellent  results.  For  the  same 
reason,  and  because  of  its  mechanical  texture,  it  is 
greatly  valued  as  a  packing  material. 

Lastly,  as  is  well  known,  peat  is  in  considerable 
demand  for  litter.  Its  value  consists  chiefly  in  the 
facts  that  it  is  able  to  absorb  far  larger  amounts  of 
moisture  than  any  other  substance  used  for  bedding, 
that  it  is  a  good  deodorizer,  and  for  a  considerable 
period  almost  entirely  prevents  the  decomposition 
of  nitrogenous  and  other  organic  substances. 
Further,  it  is  springy  and  durable,  and  keeps  the 
feet  of  the  animals  standing  on  it  in  a  perfectly 
healthy  condition. 

Commenting  on  the  position  of  peat  generally, 
Dr.  Dachnowski  writes : 

"  Peat  can  hardly  be  classed  as  a  satisfactory  raw 
material  for  making  any  of  the  more  complicated 
products  under  the  usual  conditions  existing  in  Ohio, 
where  other  and  established  substances  are  already 
to  be  had  in  any  desired  quantity  and  at  satisfactory 
prices.  Moreover,  these  products  are  obtained  from 
peat  only  by  large  investment  of  capital,  and  in 
most  cases  cannot  be  manufactured  before  the  plant 
has  passed  through  a  long  experimental  period, 
which  must  be  properly  provided  for  by  a  consider- 
able fund  established  for  the  purpose.  The  simple 
products,  peat  litter,  mull,  mattresses,  packing 
material,  and  peat  fertilizer  litter,  have  a  much 
greater  chance  of  being  quickly  made  profitable, 
because  some  of  them  are  already  on  the  market,  and 
present  uses  for  which  the  peat  is  especially  adapted. 
Moreover,  the  processes  of  preparation  are  simple, 
and  the  cost  of  equipment  for  their  manufacture 
with  tried  machinery  is  so  low  that  moderate  ex- 
penditure will  fully  equip  a  plant  to  produce  them, 


PEAT  AND  ITS  USES  43 

and  it  is  unnecessary  to  provide  for  a  long  experi- 
mental development.  It  is  apparent  therefore  that 
the  more  fibrous  kinds  of  peat,  when  they  are  found 
in  Ohio,  may  be  put  to  a  number  of  profitable  uses, 
besides  making  them  into  fuel;  while  the  black 
plastic  types,  which  are  of  frequent  occurrence,  have 
other  possibilities,  although  they  are  not  adapted 
to  the  same  uses  for  which  the  first  may  be  recom- 
mended." 

Dr.  Dachnowski's  comments  are  of  considerable 
interest  and  importance  from  my  present  standpoint. 
While  they  show  that  there  are  a  considerable  num- 
ber of  uses  to  which  peat  can  be  put,  they  indicate 
clearly  that  they  are  not  sufficiently  important  to 
make  any  large  demand  on  the  world's  peat  resources, 
and  that  the  agriculturist  who  wishes  to  make  use  of 
bacterized  peat  for  the  improvement  of  his  land  need 
not  fear  that  it  will  be  necessary  for  him  to  compete 
with  other  peat  users  for  the  raw  material. 

In  discussing  the  uses  of  peat  I  have  made  no 
reference  to  the  possibility  of  its  being  used  for  its 
own  sake  as  a  fertilizer  for  the  land.  Peat,  as  such, 
is  useless  for  the  purpose.  The  nitrogenous  and 
other  organic  substances  in  it  are  almost  insoluble, 
and  are  not  available  as  plant  foods,  while  the  facts 
that  it  is  acid  and  antiseptic  render  its  employment 
raw  definitely  harmful.  As  peat-moss  manure, 
however,  it  has  been  employed  on  the  land,  but  it 
must  be  used  with  suitable  precautions.  In  Decem- 
ber, 1911,  the  Journal  of  the  Board  of  Agriculture 
brought  this  out  very  plainly,  as  the  result  of  an 
experiment  accidentally  made  at  Kew  Gardens. 
Speaking  of  the  litter,  the  Journal  states:  "It  is 


44  THE  SPIRIT  OF  THE  SOIL 

neither  peat  nor  moss  as  these  are  understood  in 
horticulture,  and  is  entirely  unsuited  for  the  growth 
of  plants.  It  is  imported  in  the  form  of  bales, 
which  are  broken  up  in  the  stables  to  be  spread  as 
bedding  in  the  stalls.  When  it  becomes  saturated 
with  urine  and  contains  a  considerable  proportion 
of  horse -droppings,  it  is  thrown  into  a  heap  to  be 
carted  away.  Compared  with  straw-made  manure 
this  moss-litter  is  cheap,  but  is  not  looked  upon  with 
favour  by  market  gardeners.  Its  use  at  Kew  has 
been  mainly  as  a  top  dressing  for  lawns  and  borders, 
but  only  after  it  has  been  exposed  to  the  air  for 
about  six  months  and  turned  several  times.  It  has 
not  been  used  for  mixing  with  the  soil,  but  this  spring 
some  of  the  flower-beds  were  in  error  manured 
with  it.  Its  effect  on  the  health  and  growth  of  the 
plants  which  were  afterwards  put  into  these  beds 
for  the  summer  was  markedly  deleterious.  The 
plants  not  only  failed  to  start  into  growth,  but  many 
of  them  weakened  and  died,  and  as  this  was  evi- 
dently due  to  the  manure  in  the  soil,  in  which  the 
plants  were  set,  samples  of  the  soil  and  manure  were 
submitted  to  Dr.  J.  A.  Voelcker  for  analysis  and 
report." 

The  text  of  Dr.  Voelcker's  report  appears  in  the 
Journal  of  the  Board  of  Agriculture.  He  points  out 
that  nothing  in  the  analysis  led  him  to  suspect  the 
presence  of  disinfectants  or  deodorizers,  nor  were 
there  signs  of  any  mineral  acid  or  the  like.  He 
notes  that  market  gardeners  refuse  to  use  the  moss- 
litter  manure  until  it  has  been  kept  for  quite  two 
years.  He  states  also:  "  I  have  come  to  the  con- 


PEAT  AND  ITS  USES  45 

elusion  that  the  ill-effects  in  the  present  case  are  due 
to  the  marked  acidity  of  the  manure,  this  acidity 
being  due  to  organic  acids  in  the  soil  and  not  to 
mineral  ones.  I  find  in  the  soil  (in  which  the  manure 
has  been  used)  iron  compounds  present  in  the 
ferrous — or  not  fully  oxidized — conditions,  and  it 
would  seem  to  me  likely  that  these  are  the  result  of 
the  liberal  use  of  an  organically  acid  body  such  as 
the  peat-moss,  and  that  an  unhealthy,  imperfectly 
oxidized  condition  of  the  soil  has  been  brought  about. 
Very  probably,  if  the  manure  be  kept  longer  and 
allowed  to  rot  more  thoroughly,  it  becomes  more 
aerated  and  oxidized,  and  then  would  not  show  the 
ill-effects  noticed.  This,  it  seems,  is  the  possible 
explanation  of  what  has  occurred  in  the  present 
case,  and  it  is  the  explanation  at  least  which  would 
suggest  itself  to  me." 

In  a  later  chapter  it  will  be  necessary  to  consider 
the  composition  of  peat  in  some  detail,  and  to  show 
how,  in  the  case  of  humogen,  the  process  which  takes 
two  years  to  accomplish  when  the  peat  is  left  in  a 
heap  is  carried  out  in  a  few  days  by  suitable  bacterial 
treatment.  It  may  perhaps  be  as  well  to  insist  here 
that  the  addition  of  humogen  to  the  soil  is  not  under- 
taken so  much  with  the  object  of  enriching  the  soil 
with  the  nitrogenous  and  other  organic  compounds 
contained  in  the  peat,  but  that  it  is  designed  more 
particularly  as  a  medium  to  facilitate  the  growth  oi 
the  bacteria  with  which  it  is  inoculated,  and  to 
enable  them  to  work  vigorously  in  changing  the 
nitrogen  of  the  air  into  nitrogenous  plant  food. 


CHAPTER  V 

FIXATION  OF  NITROGEN  BY  LEGUMINOUS  PLANTS 

Beneficial  effect  of  growing  leguminous  plants — Liebig  and  the 
chemical  era — A  fundamental  error  corrected  by  Lawes  and 
Gilbert — Their  experiments  on  legumes — Pasteur,  Schloesing, 
and  Miintz's  discovery — Warrington's  solution  of  the  nitro- 
gen problem  for  non -legumes — Hellriegel  and  Wilfarth's 
paper — Their  experiments  on  legumes — Behaviour  of  the 
plants  explained — Importance  of  bacteria — Ward's  inocula- 
tion of  legumes — Beyerinck's  Bacillus  radicicola — Nobbe's 
culture — Experiments  in  the  United  States  and  in  England — 
Conclusions  of  the  Board  of  Agriculture — Work  at  King's 
College — Field  experiments  with  nitrobacterin — Successes 
and  failures — Unfavourable  conditions — Disappointments — 
Nature  of  benefit  to  be  expected — The  Bacillus  radicicola — 
Mechanism  of  symbiosis — Chemistry  of  the  process — 
Effect  of  over-rich  soils — Balance  between  plant  and  bac- 
teria— A  trade  analogy — Hopefulness  of  outlook. 

FROM  the  earliest  days  of  agriculture  practical  men 
have  recognized  the  fact  that  the  fertility  of  the  soil 
was  increased  by  the  growing  in  it  of  leguminous 
crops.  It  is  only  within  the  memory  of  living  man, 
however,  that  it  has  been  possible  to  state  definitely 
what  actually  occurs  in  connection  with  leguminous 
plants.  A  convenient  date  from  which  to  start 
tracing  out  the  stages  through  which  the  whole 
problem  relating  to  leguminous  plants  has  been 
carried  is  the  year  1840.  It  was  then  that  the 

46 


FIXATION  OF  NITROGEN  47 

German  professor  Liebig  presented  to  the  British 
Association  the  famous  report  afterwards  published 
as  a  book  on  Chemistry  in  its  Application  to  Agri- 
culture and  Physiology.  By  applying  the  exact 
methods  of  chemistry  to  agriculture  Liebig  succeeded 
in  establishing  that  plants  derive  the  Carbon  of 
their  tissues  from  the  Carbon  Dioxide  of  the  air,  and 
not  from  the  Carbon  compounds  that  may  be  present 
in  the  soil.  He  did  more  than  this,  for  he  pointed 
out  that  "  the  crops  on  a  field  diminish  or  increase 
in  exact  proportion  to  the  diminution  or  increase  of 
the  mineral  substances  conveyed  to  it  in  manure." 
In  one  essential  point,  however,  he  fell  into  error. 
He  came  to  regard  the  Ammonia  of  the  air  as  analo- 
gous with  the  Carbon  dioxide  in  the  air,  and  preached 
the  doctrine  that  the  plants  were  able  to  derive  their 
nitrogenous  food  from  the  atmosphere.  In  the 
Farmer's  Magazine,  for  instance,  he  wrote : 

"  If  the  soil  be  suitable,  if  it  contains  a  sufficient 
quantity  of  alkalis,  phosphates,  and  sulphates, 
nothing  will  be  wanting.  The  plants  will  derive 
their  Ammonia  from  the  atmosphere  as  they  do 
Carbonic  Acid." 

Liebig's  discoveries  were  of  classic  importance, 
partly  because  of  the  valuable  contribution  they 
made  to  agricultural  knowledge,  but  still  more 
because  of  the  stimulus  they  gave  to  agricultural 
research  along  exact  lines  of  experiment.  He  had 
not,  however,  found  the  whole  truth.  His  patent 
manure,  when  tried  in  the  field,  was  a  failure,  partly 
because  he  presented  his  mineral  foods  to  the  plants 
in  forms  unsuitable  for  their  absorption,  and  partly 


48  THE  SPIRIT  OF  THE  SOIL 

because  of  his  mistaken  view  of  the  way  in  which 
plants  obtained  theft  Nitrogen. 

Lawes,  the  pioneer  experimenter  on  agriculture  in 
England,  whose  work  at  Rothamsted  had  been  for 
some  years  in  progress,  flatly  denied  the  accuracy  of 
several  of  Liebig's  conclusions,  and  as  a  result  of 
further  experiments  conducted  by  himself  and 
Gilbert,  made  several  important  discoveries  in  con- 
nection with  mineral  manures.  These  do  not  con- 
cern us  here ;  what  is  of  importance  from  our  present 
standpoint  is  that  by  1855  Lawes  and  Gilbert  had 
established  that — 

1.  The  beneficial  effect  of  fallowing  lies  in  the 
increase  brought  about  in  the  available  nitrogen 
compounds  in  the  soil. 

2.  Non  -  leguminous  plants  require  a  supply  of 
some   nitrogenous   compounds,    nitrates   and   Am- 
monium salts  being  about  equally  good.  The  amount 
of  Ammonia  obtainable  from  the  atmosphere  is  in- 
sufficient for  the  needs  of  crops.    Leguminous  plants 
behave  abnormally. 

The  experiments  had  been  conducted  on  the  fol- 
lowing lines:  A  long  list  of  plants,  leguminous  and 
others,  had  been  grown  in  surroundings  free  from 
Ammonia  or  any  Nitrogen  compound.  The  soil  in 
which  they  grew  had  been  burnt;  the  air  furnished 
them  was  washed  and  purified,  but  they  were  sup- 
plied with  everything  necessary  in  the  form  of 
mineral  foods.  All  but  the  leguminous  plants 
languished  and  died.  The  leguminous  plants,  how- 
ever, were  found  to  flourish.  They  assimilated  large 
quantities  of  Nitrogen  into  their  tissues,  and  the  soil 


FIXATION  OF  NITROGEN  49 

in  which  they  were  growing  was  found  to  become 
richer  and  richer  in  nitrogen  compounds. 

To  the  chemist  these  results  were  a  mystery,  and 
it  was  not  until  a  fresh  method  of  attack  was  devised 
that  the  truth  emerged. 

While  Liebig,  Lawes,  Gilbert,  and  others,  were  dis- 
cussing agricultural  problems  purely  from  the 
chemical  standpoint,  Pasteur  had  begun  to  show  the 
paramount  importance  of  bacteria.  It  was  estab- 
lished by  him  that  putrefaction  and  decomposition 
were  brought  about  by  the  action  of  bacteria,  and 
the  successes  he  had  obtained  in  combating  terribly 
serious  plant  diseases  in  France  had  been  so  sen- 
sational as  to  attract  those  interested  in  agriculture 
to  the  importance  of  bacteria.  It  seemed  possible 
that  bacteria  might  be  closely  connected  with  the 
changes  going  on  in  the  soil. 

The  first  of  a  series  of  classical  experiments  was 
published  in  1877.  In  that  year  Schloesing  and 
Miintz  allowed  some  sewage  water  to  trickle  very 
slowly  through  a  filter  of  sand  and  limestone.  During 
the  first  twenty  days  of  the  experiment  the  Ammonia 
in  the  sewage  passed  unchanged.  Then  it  was 
noticed  that  some  of  it  was  changed  into  nitrate,  and 
after  a  short  time  it  was  found  that  all  the  Ammonia 
which  went  in  at  one  end  of  the  filter  .was  changed 
to  nitrate,  and  emerged  at  the  other  end  of  the  filter 
in  the  form  of  nitrate.  If  the  phenomenon  had  been 
purely  a  chemical  one,  there  was  a  mystery  as  to  why 
the  filter  should  be  inactive  for  the  first  twenty  days ; 
but  if  it  was  connected  with  the  growth  of  living 
organisms,  it  was  natural  that  time  would  have  to 

4 


50  THE  SPIRIT  OF  THE  SOIL 

elapse  to  enable  them  to  grow.  To  test  the  accuracy 
of  this  view  Chloroform  was  passed  through  the 
filter.  The  change  of  Ammonia  to  nitrate  at  once 
ceased,  but  on  removing  the  Chloroform  and  adding 
a  little  turbid  water  extract  of  dry  soil  to  the  filter 
the  action  started  again.  The  experiment  proved 
conclusively  that  bacterial  action  was  responsible  for 
the  change. 

The  publication  of  this  paper  furnished  Warring- 
ton,  who  was  working  at  Rothamsted  on  the  problem 
of  soil  Nitrogen,  with  the  key  to  the  solution.  He 
proved — 

1.  Nitrification  in  the  soil  was  stopped  both  by 
Chloroform  and  by  Carbon  bisulphide. 

2.  Solutions  of  Ammonium  salts  could  be  nitri- 
fied by  adding  a  trace  of  soil. 

3.  The    change    occurred    in    two   stages,    two 
different  bacteria  being  involved  in  the  process,  the 
Ammonia  becoming  first  of  all  nitrite  (NO2)   and 
then  nitrate  (NO3). 

So  was  solved  the  mystery  as  to  how  non-legu- 
minous plants  obtained  their  nitrogenous  food.  It 
became  generally  (if  not  quite  accurately)  recognized 
that  in  whatever  form  of  manure  Nitrogen  might  be 
added  to  the  soil,  the  plants  got  practically  nothing 
but  nitrates  as  the  source  of  their  nitrogenous  food. 

It  was  nearly  ten  years  before  the  problem  as 
affecting  leguminous  plants  was  solved.  In  1886  the 
classical  paper  clearing  up  the  difficulty  was  pub- 
lished by  Hellriegel  and  Wilfarth.  They  grew 
several  series  of  plants  in  sand,  adding  the  food  con- 
stituents as  they  desired,  and  they  found  that  the 


FIXATION  OF  NITROGEN  51 

growth  of  non-leguminous  plants  was  directly  pro- 
portional to  the  amount  of  nitrate  that  they  supplied. 
In  the  case  of  leguminous  plants  there  was  no  rela- 
tion between  the  supply  of  nitrate  and  the  growth 
of  the  plant.  If  nitrate  was  not  supplied  to  the 
leguminous  plant  after  the  seedling  stages  had  been 
passed,  the  growth  of  the  plant  was  arrested  for  a 
short  time,  and  then  it  either  died  or  started  to  grow 
again  and  did  well.  Further,  on  analyzing  the  soil, 
they  discovered  that  whereas,  as  might  have  been 
expected,  there  was  always  rather  less  nitrate  in  the 
pots  in  which  non-leguminous  plants  had  been 
grown  than  at  the  start  of  the  experiment,  in  the 
case  of  the  pots  containing  the  leguminous  plants 
the  soil  had  been  considerably  enriched  with  nitrogen. 
In  three  cases,  for  instance,  the  gain  amounted  to 
0*910,  1*242,  and  0*789  grammes  per  pot  respectively. 

Botanists  had  already  noted  that  leguminous 
plants  were  peculiar  in  the  fact  that  their  roots  con- 
tained swellings  or  nodules,  and  without  appreciating 
the  bearing  of  the  discovery,  had  remarked  that 
these  swellings  or  nodules  contained  bacteria. 
Hellriegel  and  Wilfarth,  however,  found  in  the 
experiments  they  made  in  growing  leguminous  plants 
in  sterilized  sand  that  all  the  plants  that  lived  con- 
tained these  remarkable  swellings  on  their  roots,  and 
they  reached  at  once  the  right  conclusion  that  legu- 
minous plants  had  apparently  the  power  of  obtaining 
nitrogenous  food  material  from  the  air  because  of  the 
bacteria  harboured  in  their  roots. 

At  last  the  great  puzzle  had  been  solved,  and  it 
was  found  that  the  difference  that  seemed  to  mark 


52  THE  SPIRIT  OF  THE  SOIL 

out  leguminous  plants  as  distinct  from  all  others  was 
apparent  rather  than  real.  The  great  generaliza- 
tions, however,  emerged: 

1.  Plants  derive  their  nitrogenous  food  material 
from  the  foods  present  in  the  soil,  and  not  from  any 
gases  in  the  air. 

2.  The  nitrogenous  plant  foods  present  in  the  soil 
are  either  directly  or  indirectly*   derived  almost 
entirely  from  the  Nitrogen  of  the  soil  air,  which  is 
combined  to  form  a  suitable  plant  food  by  the 
bacteria  living  in  the  soil. 

This  discovery  was  obviously  of  fundamental 
importance.  Botanists  had  hitherto  regarded  the 
soil  as  a  complex  mixture  of  chemicals  from  which 
the  plants  derived  their  food.  Now,  however,  they 
began  to  appreciate  the  fact  that  the  earth's  surface 
was  no  inert  mass  of  soil,  but  was  the  seat  of  myriads 
of  living  organisms  necessitating  the  closest  study. 

The  discovery  made  by  Hellriegel  and  Wilfarth 
was  rapidly  followed  up.  A  year  after  they  had 
announced  the  main  facts,  Marshall  Ward,  by  careful 
study  of  the  tubercles  of  leguminous  plants,  traced 
the  whole  process  of  nodule  formation  from  the 
infection  of  the  root  hairs  of  the  plant  by  some  soil 
organism  up  to  the  formation  of  the  mature  nodule, 
and  showed  that  the  tubercles  could  be  produced  at 
will  by  the  inoculation  of  the  roots  with  soil  infusions. 
In  1888  Beyerinck  isolated  the  organism  by  growing 

*  When  such  a  substance  as  stable  manure  is  added  to  the 
land,  the  nitrogenous  bodies  which  it  contains  are  plant 
residues,  and  these  have,  either  directly  or  indirectly,  derived 
their  Nitrogen  substance  from  the  Nitrogen  combined  by 
bacteria. 


--I 


\    * 


r     >•    I 

I 


J 


FIG.    3 

BACILLUS  RADICICOLA. — This  bacillus  is  found  in  the  nodules  of  leguminous 
plants,  only  lives  in  symbiosis,  and  combines  the  nitrogen  of  the  soil  air  to 
form  nitrogenous  food  material.  The  beaded  rod  form,  and  also  the  V- 
and  Y-shaped  groups,  are  characteristic. 


FIG.   4 

AZOIOBACTER  CHROOCOCCUM  is  found  in  all  fertile  soils  and,  living  by  itself, 
enriches  the  soil  in  nitrogenous  food  material  available  for  all  classes  of 
plants.  It  is  through  its  activities  that  soil  which  is  rever  manured  can 
maintain  its  fertility.  The  trees  of  all  virgin  forests  and  most  wood- 
lands depend  on  it  exclusively  for  t  leir  nitrogenous  food.  It  is  ovoid 
in  form. 


FIXATION  OF  NITROGEN  53 

it  on  a  pure  culture  medium,  and  named  it  Bacillus 
radicicola. 

Two  years  later,  in  1890,  Prazmowski  succeeded 
in  inoculating  the  roots  of  bean  plants  growing  in 
sterilized  soils,  and  in  obtaining  luxurious  growth  by 
simply  watering  the  plants  with  a  liquid  culture  of 
the  organism. 

It  was  when  this  stage  had  been  reached  that  the 
direct  commercial  application  of  the  knowledge 
newly  obtained  first  fired  the  imagination  as  a  means 
of  enormously  increasing  the  earth's  fertility.  The 
enthusiasm  was  thoroughly  justified,  for  those 
familiar  with  the  amazing  efficiency  of  bacterial 
action,  and  familiar,  too,  with  the  results  obtained 
when  the  conditions  of  growth  could  be  satisfactorily 
controlled,  as  in  the  hothouse,  were  confident  that 
only  a  little  more  experience  was  necessary  for 
similar  results  to  be  obtained  in  the  field. 

Professor  Nobbe  of  Germany  was  the  first  to  try 
and  capture  the  market.  His  method  was  to  collect 
the  bacteria  from  various  leguminous  nodules,  plant 
them  in  bottles  containing  nutrient  gelatine,  and 
sell  them  under  the  trade  name  of  Nitragin.  Some 
of  the  results  Nobbe  obtained  were  satisfactory,  but 
the  percentage  of  failures  was  so  great  that  the 
method  was  to  a  large  extent  discredited,  just  as  the 
imperfections  of  method  employed  with  Koch's 
tuberculin  in  the  early  stages  resulted  in  the  dis- 
crediting of  a  principle  thoroughly  sound. 

Nobbe's  work  had  one  good  result,  however.  The 
successes  obtained  had  been  such  that  in  1901  the 
United  States  Department  of  Agriculture  com- 


54  THE  SPIRIT  OF  THE  SOIL 

menced  "  a  scientific  investigation  of  the  root- 
nodule  organism  with  a  view  of  making  practicable 
for  use  in  the  United  States  the  pure-culture  method 
of  inoculation."  It  was  not  long  before  the  causes 
of  Nobbe's  failures  became  apparent.  The  function 
of  the  nodule  bacteria  is  to  fix  free  nitrogen  from  the 
air.  When  they  were  in  such  an  environment  as 
gelatine  with  combined  nitrogen  in  abundance  they 
became  over-fed  and  lazy,  lost  their  virulence,  and 
no  longer  had  the  power  to  force  their  way  into  the 
roots  of  leguminous  plants  and  form  nodules.  The 
American  investigators  soon  improved  on  Nobbe's 
methods.  They  used  a  Nitrogen-free  medium  for 
cultivating  their  bacteria,  and  thus  increased  the 
Nitrogen-fixing  power  of  the  bacteria.  When  this 
stage  had  been  reached  the  bacteria  were  dried  on 
cotton-wool  and  distributed.  In  the  course  of  the 
two  years,  1903  and  1904,  over  12,000  packages 
were  sent  out  free  to  farmers  in  the  various  districts 
of  the  United  States,  and  the  report  published  in 
January,  1905,  showed  that  74  per  cent,  of  the  trials 
were  successful — that  is,  gave  an  increase  of  crop  as 
a  result  of  inoculation. 

These  experiments  aroused  the  interest  of  the 
Board  of  Agriculture  and  Fisheries  in  this  country, 
and  they  invited  the  co-operation  of  thirteen  agri- 
cultural colleges  and  experiment  stations  to  try 
experiments  with  the  American  culture.  The 
Journal  of  the  Board  of  Agriculture  for  February, 
1906,  however,  issued  a  most  pessimistic  report  as 
to  the  results,  stating  that  "  the  negative  results 
exceed  the  positive  in  number,  both  in  plot  experi- 


FIXATION  OF  NITROGEN  55 

ments    and    under    agricultural    conditions."     The 
summing  up  of  the  report  was  as  follows : 

"  As  a  result  of  all  the  reported  experiments,  it 
seems  evident  that  the  cultures  used  were  not 
uniform;  it  is  not  possible,  however,  to  determine 
the  extent  to  which  the  failures  are  to  be  attributed 
to  this  cause.  It  seems,  however,  from  the  positive 
results  recorded,  that  not  only  are  these  cultures 
sometimes  able  to  produce  nodules  on  the  roots  of 
plants  new  to  a  neighbourhood,  but  that  even  in 
cases  where  the  leguminous  crop  had  been  grown  in 
the  previous  year  benefit  may  be  derived  from 
inoculation. 

"It  is  quite  evident  that  the  subject  of  plant 
inoculation  in  this  country  has  not  yet  passed  the 
experimental  stage,  and  more  work  is  required  before 
one  can  feel  at  all  justified  in  recommending  either 
method  for  adoption  on  a  field  scale;  nevertheless, 
the  positive  results  obtained  may  lead  farmers  to 
hope  that  in  the  future  benefit  may  be  derived  in 
some  instances  at  least  from  the  treatment  of  the 
soil,  or  the  seed  before  sowing,  with  inoculating 
materials  preparatory  to  growing  leguminous  crops." 

It  is  unfortunate  that  the  Board  of  Agriculture 
and  Fisheries  did  not  see  its  way  clear  to  help  in 
carrying  out  the  further  work  required,  for  the 
results,  though  admittedly  unsatisfactory,  indicated 
clearly  that  a  great  future  lay  before  the  method  of 
soil  inoculation.  Thus,  in  Scotland  an  acre  of 
inoculated  beans  yielded  3,070  pounds  of  beans, 
against  1,800  pounds  from  an  acre  non-inoculated,  a 
gain  of  70  per  cent.  In  Leicestershire  a  half -acre  plot 
of  treated  peas  yielded  when  threshed  108  stones ; 
a  half -acre  plot  untreated  only  66  stones.  At  Woburn 


56  THE  SPIRIT  OF  THE  SOIL 

treated  Melilotus  gave  23  per  cent,  heavier  crop  than 
untreated.  At  Aberdeen,  "  on  a  farm  where  the 
soil  is  peaty,  and  clover  had  never  grown  well,  the 
treatment  has  been  remarkably  successful,  producing 
a  thicker  covering  of  clover  and  a  much  stronger 
growth.  The  difference  has  increased  between 
October  and  the  present  time  in  an  extraordinary 
way." 

Even  before  the  Board  of  Agriculture  Report  had 
appeared,  in  the  autumn  of  1905,  American  experi- 
menters had  discovered  a  cause  of  failure.  The 
bacteria  when  sent  out  on  dried  cotton-wool  only 
retained  their  vitality  for  a  period  of  from  six  weeks 
to  a  couple  of  months,  a  fact  that  in  itself  amply 
explained  the  negative  results  obtained  in  many  of 
the  experimental  stations  in  this  country.  For  it 
was  admitted  that  in  several  instances  the  cultures 
had  been  kept  as  much  as  six  or  eight  months  before 
being  applied  to  the  land. 

While  Amferica  was  carrying  out  field  experiments 
on  this  lavish  scale  with  cultures  of  the  Bacillus 
radicicola,  the  attempt  was  being  made  by  Professor 
Bottomley  in  the  Botanical  Laboratories  of  King's 
College,  London,  to  clear  up  several  points  that  were 
obscure  in  the  life  history  of  the  bacteria,  and  to 
determine  accurately  the  nature  of  the  chemical 
changes  involved.  When  the  Board  of  Agriculture 
discontinued  their  field  experiments  he  decided  to 
invite  the  co-operation  of  farmers,  professional 
growers,  and  others  interested,  to  test  the  efficiency 
of  the  pure  cultures  with  which  he  had  been  working 
at  King's  College.  To  send  out  the  bacteria  on 


FIXATION  OF  NITROGEN  57 

cotton-wool,  as  had  been  done  in  America,  would 
clearly  have  been  to  invite  failure,  and  several  tests 
were  made  to  find  out  the  most  suitable  medium. 
After  many  trials  it  was  found  that  when  the  bacteria 
were  mixed  with  earth  and  the  whole  was  dried,  the 
bacteria  lived,  and  retained  their  vitality  in  any 
case  for  several  months,  and  in  some  instances  for  as 
much  as  three  years. 

During  the  years  1906  and  1907  more  than  a 
thousand  packages  of  the  material  were  distributed 
throughout  the  country,  and  in  over  80  per  cent,  of 
cases  the  reports  showed  that  an  increase  of  crop 
had  resulted  from  its  use. 

That  the  results  obtained  justified  the  enthusiasm 
aroused  can  readily  be  understood  from  the  nature 
of  the  reports  received.  They  are  given  in  Appen- 
dix A  just  as  they  were  originally  published  seven 
years  ago,  but  the  following  short  quotations  from 
them  are  sufficient  to  prove  that  the  radicicola 
cultures  showed  promise  of  revolutionizing  the 
everyday  practice  both  of  horticulture  and  agri- 
culture : 

"  The  peas  were  a  great  success.  Inoculation  of 
soil  and  seed  returned  a  good  30  per  cent,  more  than 
only  seed  inoculation,  and  the  seed  inoculation 
showed  a  good  20  per  cent,  better  crop  than  the 
farmyard  manured  peas.  Inoculation  in  both  cases 
rendered  a  fortnight  earlier  marketing  possible  over 
the  manured." 

"  The  inoculated  clover  was  taller  by  3  inches 
than  the  uninoculated." 

'  The  inoculated  Broad  Beans  were  up  a  week  and 
a  half  before  those  not  treated,  and  were  very  much 


58  THE  SPIRIT  OF  THE  SOIL 

greener  and  more  weight.  Two  rows  inoculated, 
65  yards  long,  gave  4J-  pots.  Two  rows,  not  inocu- 
lated, 65  yards  long,  gave  3  pots." 

'  The  inoculated  Beans  were  quite  three  weeks 
earlier  than  the  others." 

"  I  put  the  inoculation  liquid  on  about  a  quarter 
of  an  acre  of  grass  and  clover  as  a  top-dressing.  In 
about  a  week  I  could  see  an  improvement,  and  the 
clover  was  far  higher  and  thicker  than  the  rest  of  the 
field  right  on  until  it  was  cut.  There  was  double  the 
quantity  on  it,  and  it  was  the  same  with  the  after- 
math; it  came  up  the  second  time  far  thicker  and 
stronger  than  the  rest  of  the  field." 

"  From  a  quarter  of  an  acre  of  peas  inoculated  I 
picked  33f  pots  (42  pounds  to  the  pot),  selling  them 
for  £7  i8s.  gd.  From  a  quarter  of  an  acre  not  inocu- 
lated, but  dressed  with  i  cwt.  superphosphate  and 
\  cwt.  sulphate  of  potash,  I  picked  only  14  pots, 
selling  them  for  £2  5s.  6d." 

From  certain  points  of  view  the  very  success  of 
the  results  obtained  proved  unfortunate.  Little 
was  known  about  the  bacteria  at  the  time,  or  of  the 
conditions  necessary  to  their  growth.  Experience  in 
the  form  of  negative  results  had  yet  to  show  that  the 
bacteria  were  unable  to  grow  in  acid  soils,  and  that 
in  such  conditions  it  was  necessary  to  resort  to 
liming  to  correct  the  acidity ;  that  the  bacteria  would 
not  grow  in  land  already  rich  in  nitrates ;  that  they 
were  sensitive  to  adverse  conditions  of  weather  and 
climate;  that  their  efficiency  would  be  impaired 
either  when  the  plant  concerned  was  too  weak,  in 
which  case  the  weaker  bacteria  could  force  an 
entrance  into  the  roots,  or  too  strong,  when  the  roots 
might  succeed  altogether  in  resisting  bacterial 


FIG.   5 

The  value  of  the  auximones  in  promoting  healthy  growth  is  strikingly 
illustrated  above.  Each  of  the  treated  plants  (Primula  malacoides] 
received  the  water  extract  of  ribth  of  an  ounce  of  humogen,  but 
otherwise  the  treatment  was  identical.  The  increase  of  growth, 
flowering,  and  of  root  development  in  the  treated  plant  (on  the 
right)  is  very  evident,  but  typical. 

(Dr.  Rosenheim,  University  of  London,  King's  College.) 


FIXATION  OF  NITROGEN  59 

invasion.  These  were  some  of  the  causes  that  led  to 
disappointing  negative  results.  There  were  occasions, 
too,  when  failure  resulted,  because  the  directions  for 
preparing  the  bacterial  culture  on  the  farm  were 
not  accurately  followed.  Sometimes  soils  were 
treated  that  were  deficient  in  phosphates  and  potash, 
and  naturally  the  bacteria  were  powerless  to  make 
up  for  the  absence  of  these  minerals. 

For  these  and  similar  reasons  there  were  several 
failures  with  the  cultures.  The  feeling  of  disap- 
pointment among  growers  was  great,  and  naturally 
the  men  who  had  gone  to  all  the  labour  and  trouble 
of  inoculating  their  seed  and  soil  only  to  find  no 
trace  of  advantage  came  dogmatically  to  the  con- 
clusion that  nitro-bacterin,  as  the  culture  was  called, 
was  no  good.  Such  failures  were  widely  advertised, 
and  as  some  of  them  occurred  at  experimental 
stations,  growers  were  discouraged  from  making 
further  attempts. 

At  this  stage  of  the  work,  however,  the  successes 
obtained  were  for  the  time  being  of  more  importance 
than  the  failures,  for  the  successes  proved  definitely 
that  in  England,  if  the  conditions  were  such  as  to 
favour  inoculation,  the  following  important  benefits 
resulted : 

1.  An  increased  yield  of  the  leguminous  crop. 

2.  The  improvement  of  the  land  for  succeeding 
crops  through  the  addition  of  organic  nitrogen  to  the 
soil. 

3.  Increase  of  the  nitrogenous  content  of  inocu- 
lated crops,  carrying  with  it  an  increase  in  feeding 
value. 


6o  THE  SPIRIT  OF  THE  SOIL 

4.  In  many  cases  hastened  maturing  of  plants, 
thus  allowing  the  earlier  marketing  of  produce  with 
enhanced  value. 

The  fact  that  it  was  possible  in  certain  conditions 
to  obtain  such  results  made  it  plain  that  it  was 
worth  while  to  continue  working  at  the  problem. 
As  will  be  seen  in  later  chapters,  the  further  work 
done  has  led  to  results  that  at  the  time  were  un- 
suspected, and  that  are  far  more  important  than 
were  dreamt  of  at  the  time.  Before  considering 
them,  however,  it  will  be  well  to  conclude  this 
chapter  with  a  short  account  in  view  of  modern 
knowledge  of  the  Bacillus  radicicola  in  its  relation  to 
leguminous  plants. 

The  B.  radicicola  is  a  small  rod-shaped  organism 
that  is  found  widely  distributed  in  nature.  For 
some  reason,  as  yet  unexplained,  it  is  able  to  attack 
the  roots  of  the  leguminous  plants.  It  forces  its  way 
into  the  delicate  root  hairs  of  the  growing  legumes, 
and  penetrates  into  the  interior  of  the  root  branches. 
When  once  it  has  effected  an  entrance  it  increases  in 
size  and  changes  its  shape,  appearing  sometimes  as 
irregular  rods  and  at  others  as  V  or  Y  shaped 
organisms.  For  its  growth  it  requires  food  in  the 
form  of  sugar  and  mineral  salts,  and  these  it  takes 
from  the  roots  of  the  leguminous  plants  which  it  has 
invaded.  There  can,  as  will  be  seen  presently,  be 
little  doubt  but  that  the  leguminous  plant  resists 
the  entry  of  the  bacillus.  The  bacillus,  however, 
forces  its  way  in,  demanding,  as  it  were,  rights  of 
partnership,  and  once  it  has  established  itself  and 
secured  food  and  shelter,  it  offers  to  its  host  in  return 
Nitrogen  that  it  can  take  from  the  air,  and  give  to 


FIXATION  OF  NITROGEN  61 

the  plant  in  a  form  in  which  it  can  absorb  it .  Present 
knowledge  does  not  make  it  possible  to  state  in 
definite  chemical  symbols  what  are  the  exact  Nitro- 
gen compounds  formed.  What  can  be  seen  when 
the  bacteria  are  cultivated  in  pure  cultures  is  that  a 
slime  forms  round  the  bacteria.  The  mass  of  slime 
and  bacteria  can  be  shown  to  consist  of  Carbon, 
Oxygen,  Hydrogen,  and  Nitrogen,  and  as  the  only 
source  of  the  nitrogen  is  the  air,  it  can  be  stated  defi- 
nitely that  the  bacteria  have  seized  the  Nitrogen 
from  the  air  and  combined  it  with  Carbon,  Oxygen, 
and  Hydrogen.  It  can  also  be  stated  definitely  that 
the  nitrogen  compounds  so  formed  are  such  that 
the  plant  can  absorb  them  and  build  them  into  the 
nitrogenous  bodies  or  proteins  that  their  tissues 
require. 

In  the  early  stages  of  the  process,  as  we  have  seen, 
it  is  the  bacteria  that  are  the  attacking  party.  The 
leguminous  plant,  however,  waits  and  takes  its 
revenge.  The  V  or  Y  shaped  bodies  become  more 
numerous,  but  as  the  plant  grows  older  many  of  them 
are  dissolved  and  absorbed.  Some,  however,  remain 
behind,  and  when  the  plant  eventually  dies  they 
migrate  back  into  the  soil  and  await  their  oppor- 
tunity for  invading  the  roots  of  the  next  crop  of 
leguminous  plants. 

If  the  ground  in  which  leguminous  plants  are 
grown  is  rich  in  nitrogen,  as,  for  instance,  as  a 
result  of  liberal  treatment  with  well-rotted  stable 
manure  or  with  nitrates,  no  nodules  are  formed  on 
the  plant  roots.  A  natural  explanation  is  that  the 
growth  of  such  plants  is  vigorous,  and  that  their 
oot  hairs  are  strong  enough  to  resist  the  attacks  of 


62  THE  SPIRIT  OF  THE  SOIL 

the  bacteria.  In  much  the  same  way  it  has  been 
found  that  seeds  may  be  able  to  resist  inoculation — 
this  difficulty  in  practice  can  be  easily  overcome — 
owing  to  a  protective  chemical  substance  which 
prevents  the  bacteria  from  digesting  the  cell  wall  and 
forcing  an  entry:  a  phenomenon  roughly  analogous 
with  the  fact  that  the  cells  of  the  stomach  and 
intestines  possess  chemical  substances  that  prevent 
their  being  attacked  by  the  digestive  ferments  pre- 
pared in  the  alimentary  canal.  In  such  a  case 
inoculation  is  obviously  useless. 

From  several  standpoints  a  great  deal  depends  on 
the  health  and  vigour  of  the  root.  As  we  have  seen, 
if  the  root  is  very  vigorous  the  bacteria  cannot  enter 
it,  and  in  such  conditions  leguminous  crops  planted 
in  the  soil,  instead  of  enriching  it  in  nitrogenous 
bodies,  would  deplenish  its  store  of  Nitrogen. 
Suppose,  however,  that  one  goes  to  the  other 
extreme,  and  that  the  plants  are  starved  and  feeble. 
In  such  a  case  the  roots  can  put  up  no  resistance  to 
the  bacteria.  These  will  force  an  entry,  but  the 
roots,  instead  of  giving  harbourage  only  to  the  most 
vigorous  bacteria,  will  admit  even  the  weaker  strains, 
such,  perhaps,  as  will  be  sluggish  in  forming  nitrogen 
compounds,  and  in  consequence  the  plants  will  gain 
little  from  their  association  with  the  bacteria.  It  has 
even  been  suggested  by  some  bacteriologists  that  the 
just  balance  may  be  overset  and  the  bacteria  become 
too  strong  for  the  plants,  and  the  latter  be  unable  to 
insist  on  the  former  fulfilling  their  side  of  the  con- 
tract and  giving  up  a  fair  share  of  the  nitrogen  com- 
pounds that  they  have  prepared.  In  such  a  case 


FIXATION  OF  NITROGEN  63 

the  bacteria  would  be  mere  parasites,  taking  the 
sugars  and  salts  they  required  from  the  plants 
without  furnishing  a  corresponding  value  in  return 
in  the  form  of  nitrogenous  foods. 

This  may  seem  to  some  a  fanciful  pressing  of  a 
trade  analogy,  but  it  has  its  foundation  in  experi- 
mental fact,  for  from  time  to  time  it  has  proved 
beneficial  to  give  light  top-dressings  of  Nitrate  to 
new  fields  of  alfalfa.*  This  would  increase  the 
vigour  and  resisting  power  of  the  young  plants.  In 
this  way  only  vigorous  bacteria  would  be  able  to 
force  an  entry,  and  the  ultimate  fixation  of  nitrogen 
would  be  greater.  Heavier  applications  of  nitrogen 
would  prove  objectionable  as  the  bacteria  would  be 
altogether  excluded. 

Considerations  such  as  these  are  both  interesting 
and  important.  They  suggest  why  some  of  the 
earlier  experiments  gave  negative  results,  and  hold 
out  the  greatest  encouragement  for  the  future.  Soil 
inoculation,  whether  for  leguminous  plants  alone  or 
for  all  plants,  must  be  practised  intelligently.  The 
conditions  required  for  success  are  becoming  every 
day  better  known,  and  the  time  is  not  far  distant 
when  it  will  be  possible  to  state  the  exact  degree  of 
benefit  that  can  be  looked  for  with  confidence  as  a 
result  of  soil  inoculation  in  any  given  set  of  circum- 
stances. Further,  it  is  becoming  every  day,  as  a 
result  of  the  increase  of  knowledge,  more  possible  so 
to  alter  the  environment  as  to  increase  the  circum- 
stances in  which  the  practice  of  soil  inoculation  is 
certain  to  prove  of  benefit. 

*  Bacteria  in  Relation  to  Country  Life  (Lipman) . 


CHAPTER  VI 

HUMUS 

Humus  as  the  home  of  bacteria — Soil  composed  of  mineral 
debris  and  humus — Influence  of  mineral  debris  secondary — 
Bacteria  and  plants  and  animals — The  sun  and  food  as  pro- 
ducers of  energy — Humus  as  a  source  of  energy — Life 
limited  by  the  food-supply — Mild  humus  and  raw  humus — 
Their  properties — Bacteria  as  chemical  agents — Complexity 
of  humus — Four  groups  of  compounds — Only  one  carbo- 
hydrate isolated  from  humus — Carbohydrates  and  humic 
bodies — Effect  of  boiling  carbohydrates  with  hydrochloric 
acid — Humic  acid  formed  before  humin — Difference  between 
natural  and  artificial  humic  acid — The  difference  reconciled 
— No  real  formula  for  humic  acid — Effect  of  boiling  carbo- 
hydrates with  organic  acids — Effect  of  heating  carbo- 
hydrates— Nature  of  humic  bodies  obtained — Proteins  and 
humic  bodies — Nature  of  changes  in  formation  of  peat — 
Causes  of  complexity  of  humic  bodies. 

EMPHASIS  has  been  laid  in  the  previous  chapters  on 
the  fact  that  the  attention  of  all  growers,  directed 
until  recently  on  to  the  chemical  and  mechanical 
aspects  of  the  soil,  has  during  the  last  few  years  been 
focussed  chiefly  on  the  soil  as  the  seat  of  changes 
brought  about  by  the  bacteria  that  inhabit  it.  In 
the  last  chapter,  dealing  with  the  fixation  of  nitrogen 
from  the  soil  air  by  leguminous  plants,  it  was  neces- 
sary to  refer  briefly  to  the  fixation  of  nitrogen  by 
bacteria  which  have  no  relation  with  leguminous 
plants.  These  will  have  to  be  considered  at  length 

64 


HUMUS  65 

in  the  following  chapter,  as  it  is  chiefly  they  and 
their  activities  that  are  the  subject  of  the  present 
volume.  Before  doing  so  it  is  necessary  to  form  a 
clear  idea  of  the  non-living  medium  in  which  they 
live  and  of  its  properties. 

The  soil  from  the  particular  standpoint  which  I 
am  considering  may  be  regarded  as  a  mixture  of  two 
constituents — (i)  mineral  debris,  and  (2)  decaying 
organic  matter  or  humus. 

The  mineral  debris  in  the  soil  plays  no  very  inter- 
esting part  in  connection  with  the  life  of  the  soil 
bacteria.  It  is  in  most  cases  only  soluble  with 
difficulty,  and,  with  the  exception  of  lime,  influences 
bacterial  life  rather  from  a  negative  standpoint. 
Thus,  a  clay  soil  will  retain  an  excess  of  moisture 
and  interfere  with  bacterial  growth ;  a  sandy  soil,  on 
the  other  hand,  by  allowing  excessive  drainage,  will 
unduly  parch  the  ground,  and  eventually  check 
bacterial  activities.  Conditions  well  known  to  the 
practical  agriculturist  will  bring  about  an  acid  state 
of  the  soil,  in  which  the  bacteria  will  find  growth 
impossible.  These  and  other  conditions  will  be 
considered  in  the  chapter  in  which  the  practical 
application  of  the  bacterized  peat  or  humogen  is 
discussed,  but  may  be  ignored  here,  as  they  may 
fairly  be  regarded  as  factors  superimposed  on  normal 
conditions. 

The  centre  of  bacterial  activity  is  the  humus  or 
decaying  organic  matter  in  the  soil.  Bacteria  differ 
essentially  from  plants  in  that  they  have  no  mechan- 
ism enabling  them  to  derive  their  energy  from  the 
rays  of  the  sun,  but,  like  animals,  must  secure  it  from 

5 


66  THE  SPIRIT  OF  THE  SOIL 

the  food  that  they  absorb.     This  central  fact  is 
fundamentally  important  to  a  proper  understanding 
of  the  subject.     Many  perhaps  do  not  realize  the 
magnitude  of  the  work  done  by  the  plants  in  breaking 
up  Carbon  dioxide.     The  chemist  in  the  laboratory 
can  only  achieve  it  by  an  intense  expenditure  of 
energy.     Thus  it  is  a  common  elementary  experi- 
ment to  show  that  some  such  energetic  substance 
as  Phosphorus  must  be  used  to  decompose  the  gas. 
The  Phosphorus  is  placed  in  the  Carbon  dioxide 
and  heated,  and  in  these  conditions  is  able  to  seize 
the  Oxygen  from  the  Carbon  dioxide,  and  leave  the 
Carbon    behind    in    the    form    of    black    particles. 
Another  experiment  on  which  a  chemical  lecturer 
will  insist  is  the  burning  of  a  wood  match.     Once 
the  temperature  of  the  match  is  raised  to  a  suffi- 
ciently high  point  it  burns,  the  Carbon  in  it  uniting 
with  the  Oxygen  of  the  air,  large  quantities  of  energy 
appearing  during  the  process  as  heat  and  light.     It 
is  reasonable  and  scientifically  exact  to  believe  that 
a  corresponding  amount  of  energy  would  have  to  be 
supplied  for  the  converse  process  to  take  place — • 
i.e.,  for  the  Carbon  dioxide  of  the  air  to  be  recon- 
verted into  the  wood  of  the  match.     Yet  this  is  what 
is  being  done  day  by  day  quietly  by  the  plants,  the 
energy  required  for  the  purpose  being  derived  from 
the  rays  of  the  sun  and  absorbed  by  means  of  the 
green  chlorophyll  in  the  leaves. 

The  animal  or  the  bacterium  in  taking  in  food  is 
absorbing  materials  which  are  able  to  give  him  the 
vast  quantities  of  energy  he  requires  for  his  life. 
From  the  point  of  view  of  energy  there  is  no  funda- 


HUMUS  67 

mental  difference  between  the  process  occurring 
when  a  wood  match  is  burnt  and  that  occurring  when 
a  horse  eats  a  meal  of  hay  or  corn.  The  only  differ- 
ences are  that  in  the  case  of  the  match  the  energy  is 
delivered  rapidly  and  in  the  form  of  light  and  heat, 
while  in  the  case  of  the  horse  it  is  delivered  slowly 
and  is  utilized  for  warmth,  for  locomotion,  for  per- 
forming complex  chemical  reactions,  and  so  forth. 
In  both  cases  the  underlying  principle  obtains  that 
Carbon  on  being  oxidized  or  degraded  to  form  Carbon 
dioxide  yields  energy. 

Looked  on  in  a  somewhat  similar  way  the  decaying 
organic  matter  in  the  soil,  or  humus,  may  fairly  be 
considered  as  a  unit  substance,  and  the  soil  con- 
taining it  regarded  as  a  storehouse  of  energy.  From 
time  immemorial  gardeners  and  farmers  have  recog- 
nized its  value.  Under  the  dominating  influence  of 
chemical  ideals  they  ignored  more  or  less  completely 
the  energy  factor,  and  regarded  the  manuring  of  the 
crop  as  an  act  undertaken  with  a  view  of  supplying 
to  the  plant  the  chemical  constituents  of  which  it 
stood  in  need.  In  so  doing,  of  course,  they  tacitly 
accepted  the  value  of  manure,  both  mineral  and 
other,  as  a  source  of  energy — for  what  else  is  food  in 
its  varied  forms  ? — but  they  focussed  their  attention 
on  constituents  necessary  for  plant  life,  and  only 
emphasized  energy  considerations  so  far  as  the  direct 
utilization  of  the  sun's  rays  by  the  leaves  of  the 
plant  were  concerned. 

With  the  growing  recognition  of  the  importance 
of  bacteria,  there  has  been  in  recent  years  a  marked 
increase  in  the  attention  paid  to  the  nature  and 


68  THE  SPIRIT  OF  THE  SOIL 

constitution  of  humus,  and  it  may  perhaps  be  most 
convenient  to  consider  it  first  rather  from  the 
biological  and  physical  standpoints,  and  then  from 
the  point  of  view  of  its  chemical  constitution  and 
relationships. 

The  commonplace  of  natural  history  that  the  growth 
of  living  beings  is  chiefly  conditioned  by  the  extent 
and  character  of  the  food-supply  is  abundantly  borne 
out  in  the  case  of  soil  bacteria.  Apart  from  the 
organisms  connected  with  the  fixation  of  Nitrogen  in 
leguminous  plants,  which  are  only  partially  dependent 
on  decaying  organic  matter  for  their  food-supply,  the 
growth,  development,  and  activity  of  the  soil  bacteria 
depend  on  the  abundance  and  character  of  the  humus 
in  the  soil.  It  is  this  that  provides  them  with  the 
energy  they  require  in  the  form  of  food,  which 
improves  the  moisture  and  temperature  conditions 
of  the  medium  in  which  they  live,  tending  to  keep 
the  latter  more  or  less  stable,  and  preventing  violent 
changes  in  temperature  that  would  prove  injurious 
to  their  growth.  It  is  only  for  very  broad  generaliza- 
tions such  as  these  that  one  can  regard  humus  as  a 
simple  substance  of  uniform  composition. 

Biologically  it  falls  into  two  grand  classes — the 
mild  humus  or  mull  met  with  in  arable  soils  and 
woodland,  and  the  raw  humus  found  in  heaths, 
meadows,  and  swamps. 

Mild  humus  is  either  neutral  or  alkaline  in  reaction, 
and  is  formed  in  conditions  that  allow  the  free  entry 
of  air,  and  facilitate  the  development  of  the  so-called 
aerobic  bacteria — that  is,  of  the  bacteria  that  are 
able  to  develop  in  the  presence  of  oxygen.  Raw 


HUMUS  69 

humus,  on  the  other  hand,  is  acid  in  reaction.  The 
conditions  under  which  it  has  been  formed  have 
largely  checked  the  growth  of  bacteria,  and  result  in 
putrefaction  rather  than  in  decay.  Whereas  in  the 
former  the  organic  material  liberates  Carbon  dioxide 
in  quantity — is  decomposed  in  fact  by  slow  com- 
bustion— the  latter,  acted  on  in  the  absence  of  air, 
takes  the  Oxygen  it  needs  for  the  oxidation  of  its 
Carbon  from  the  organic  substance  itself,  and 
eliminates  also  from  the  mass  such  gases  as  marsh 
gas  (CH4) .  It  is  for  this  reason  that  the  end-products 
in  the  two  cases  are  different.  In  mild  humus 
organic  bodies  are  formed  from  which  the  Nitrogen- 
fixing  bacteria  can  derive  their  energy  and  food,  and 
on  which,  too,  the  plants  can  feed  directly.  In  raw 
humus  the  end-products  are  a  mixture  of  com- 
pounds known  as  Humic  acid,  or  Humin,  that 
prevent  the  growth  of  bacteria,  that  are  in  fact  anti- 
septic, and  that  do  not  furnish  the  plants  with  food 
material  in  a  form  in  which  they  can  assimilate  it. 
Peat,  in  fact,  is  raw  humus.  It  not  only  fails  to 
undergo  decomposition  while  remaining  in  the 
swamp,  but  when  put  on  the  land  in  its  raw  state  it 
undergoes  decomposition  very  slowly,  and  definitely 
retards  the  growth  of  crops.  It  is  only  necessary 
to  contrast  peat  with  the  humus  that  can  be 
seen  as  a  rich,  dark  liquid  oozing  out  of  a  manure- 
heap  to  realize  the  difference  between  the  humus 
rich  in  the  substances  required  for  plant  food, 
and  that  in  which  available  food  substances  are 
wanting. 

In  stating  that  great  progress  may  be  looked  for 


70  THE  SPIRIT  OF  THE  SOIL 

in  agriculture  as  a  result  of  emphasizing  the  import- 
ance of  bacteria  instead  of  restricting  the  outlook  to 
the  chemical  composition  of  the  soil,  it  has  to  be 
realized  that  from  one  very  important  point  of  view 
agriculture  must  always  be  regarded  as  a  purely 
chemical  process.  It  will  always  be  possible  to 
express  what  happens  when  a  crop  has  grown  from 
seed  to  mature  plant,  by  an  analysis  of  the  completed 
plant  on  the  one  hand  and  an  estimate  of  substances 
taken  from  the  air  and  the  soil  on  the  other.  So 
long  as  the  botanist  or  agriculturist  bears  in  mind 
that,  in  so  doing  he  has  not  expressed  the  full  process 
it  is  as  desirable  to-day  as  ever  it  was  that  all 
information  possible  should  be  derived  from  the 
chemical  conditions  underlying  growth.  While  it 
is  correct  to  state  that  one  of  the  most  important 
properties  of  the  humus  is  its  power  of  enabling 
the  bacteria  to  develop  in  the  soil,  it  is  also  well 
to  bear  in  mind  that  the  value  of  the  bacteria  so 
growing  in  the  soil  lies  in  the  products  of  their 
activities,  which  are  essential  for  satisfactory  plant 
growth. 

Humus,  when  one  starts  to  consider  it  from  the 
chemical  standpoint,  is  a  highly  complex  mixture  of 
various  compounds,  which  it  has  hitherto  proved 
impossible  for  the  chemist  either  to  separate  or 
satisfactorily  to  analyze.  For  very  many  years  it 
has  formed  the  subject  of  keen  interest  and  dis- 
cussion. Naturally  enough,  perhaps,  in  early  days 
it  was  regarded  as  being  of  very  simple  composition. 
De  Saussure,  for  instance,  in  1804  described  it  as  a 
' '  brown  combustible  powder  soluble  in  Alkalies  and 


HUMUS  71 

Ammonia  compounds."  Mulder  was  one  of  the 
first  in  1849  to  attempt  really  to  describe  it  chemic- 
ally. He  explained  that  it  consisted  of  seven  organic 
compounds  closely  related  to  each  other — namely, 
Crenic  acid,  Apocrenic  acid,  Geic  acid,  Humic  acid, 
Humin,  Ulmic  acid,  and  Ulmin.  Modern  workers 
would  recognize  the  problem  as  being  one  of  far 
greater  complexity,  but  fortunately  the  early  stages 
of  any  investigation  into  it  are  easily  carried 
out  and  understood.  Few  terms  have  to  be  used, 
and  to  them  it  is  possible  to  give  a  well-defined 
meaning. 

Humus,  according  to  the  modern  views  held  as  to 
its  structure,*  can  be  divided  somewhat  artificially, 
perhaps,  into  four  chief  groups  of  substance — Crenic 
acid,  soluble  Humic  acid,  insoluble  Humic  acid,  and 
Humin.  If  a  sample  of  humus  is  taken  and  ex- 
tracted with  alkali,  a  portion  of  it,  known  as  Humin, 
is  insoluble.  On  treating  the  soluble  alkaline  liquid 
with  acid  a  precipitate  is  formed,  but  Crenic  acid 
derived  from  the  humus  remains  in  the  liquid.  If 
the  precipitate  is  boiled  with  alcohol,  a  portion  of  it 
is  soluble,  soluble  Humic  acid,  and  a  portion  in- 
soluble, insoluble  Humic  acid.  To  some  extent 
these  bodies  are  not  present  in  the  original  humus, 
but  they  represent  groups  of  bodies  that  are  present, 
and  as  the  classification  is  very  valuable  if  one 
wishes  to  get  as  clear  an  understanding  as  possible 

*  The  latter  portion  of  this  chapter  is  based  on  the  paper  by 
Professor  Bottomley  in  the  Biochemical  Journal,  June,  1915, 
"  The  Formation  of  Humic  Bodies  from  Organic  Substances." 
Those  wishing  for  fuller  details  should  consult  the  original 
paper. 


72  THE  SPIRIT  OF  THE  SOIL 

of  the  nature  of  humus,  it  may  be  well  to  set  the 
position  out  diagrammatically : 

Extract  humus,  with  alkali. 

| 

Alkaline  solution,  Acidify.  Insoluble 

|  residue. 

Acid  filtrate.  Precipitate,  boil  with  alcohol. 

Crenicacid.    Humic  acid,  soluble.    Humic  acid,  insoluble.   Humin. 

From  the  Crenic  acid  group  and  from  the  soluble 
Humic  acid  group — it  cannot  be  too  often  insisted 
that  we  are  dealing  with  groups  of  substances  and 
not  with  pure  bodies — as  many  as  twenty  distinct 
compounds  have  been  isolated,  while  so  far  the  con- 
stituents of  the  two  other  groups  (insoluble)  have 
defied  chemical  analysis.  About  the  compounds  so 
isolated  the  curious  fact  has  been  recognized  that 
only  one  of  them  is  a  carbohydrate.  A  carbohydrate 
is  a  compound  that  consists  of  a  certain  amount  of 
Carbon  combined  with  Hydrogen  and  Oxygen  in 
such  a  proportion  as  would  result  in  the  formation  of 
water.  It  can  be  expressed  generally  in  the  formula, 
CmH2nOn,  where  m  and  n  are  any  whole  numbers.  In 
view  of  the  fact  that  a  very  large  percentage  of  plant 
substance  consists  of  carbohydrates,  it  is  curious  that 
they  should  not  be  represented  largely  in  the  decom- 
position products  of  organic  material. 

In  the  course  of  the  researches  on  Nitrogen-fixing 
bacteria  at  the  Botanical  Laboratory  in  the  Uni- 
versity of  London,  King's  College,  it  became  desir- 
able to  try  and  determine  what  relation  existed 
between  carbohydrates  and  the  unknown  Humic 


HUMUS 


73 


acid  and  Humin  groups.  Exact  definitions  became 
necessary  at  the  outset  of  the  research,  and  the 
groups  were  therefore  defined  as  follows.  The  term 
Humic  acid  was  given  to  substances  thrown  down 
as  brown  colloid  precipitates  by  mineral  acids 
from  the  water  or  alkaline  extracts  of  humus,  and 
the  term  Humin  to  substances  insoluble  in  water 
and  alkalies,  but  rendered  soluble  by  fusing  with 
caustic  soda  or  potash,  from  the  solution  of  which 
Humic  acid  can  again  be  precipitated. 

Three  different  kinds  of  sugars  were  taken  as  con- 
venient carbohydrates,  Laevulose,  Sucrose,  and  Dex- 
trose, and  boiled  under  a  reflux  condenser  with  a 
3  per  cent,  solution  of  Hydrochloric  acid  for  varying 
periods  of  time.  A  series  of  colour  changes  take 
place,  and  the  colourless  solutions  turn  successively 
yellow,  red,  and  brown,  and  then  begin  to  precipitate. 
It  was  obvious  at  once  that  there  were  conspicuous 
differences  with  the  different  carbohydrates,  Lsevu- 
lose  and  Sucrose  changing  rapidly,  but  Dextrose 
going  very  much  more  slowly.  This  is  well  shown 
by  the  following  table:* 


Yellow. 

Red. 

Brown. 

Laevulose 
Sucrose         .  .      ... 
Dextrose 

i  minute 
2  minutes 
ii  ,, 

5  minutes 
8 
60 

8  minutes 

J2           „ 

90 

*  A  simple  experiment  illustrating  this  can  be  done  by  pouring 
concentrated  sulphuric  acid  on  to  a  thick  syrup  of  cane-sugar. 
By  this  violent  method  these  changes  can  be  more  or  less  well 
observed,  but  once  the  reaction  starts,  it  is  completed  almost 
immediately. 


74 


THE  SPIRIT  OF  THE  SOIL 


In  each  case  the  precipitate  first  formed  from  the 
brown  liquid  was  found  to  be  Humic  acid,  and  it  was 
not  unless  the  reaction  was  continued  that  Humin 
made  its  appearance.  The  experiment  seemed  to 
suggest  that  Humic  acid  might  be  an  intermediate 
product  between  Carbohydrate  and  Humin.  On 
testing  the  hypothesis  it  was  found  that  on  boiling 
the  Humic  acid  from  Laevulose  with  a  7*5  per  cent, 
solution  of  Hydrochloric  acid  for  four  hours,  98  per 
cent,  of  it  became  Humin,  while  on  treating  Humic 
acid  derived  from  peat  in  the  same  way  3*5  per  cent, 
of  it  became  Humin. 

The  result,  while  confirming  the  possibility  of 
Humic  acid  being  a  transition  stage  between  Carbo- 
hydrate and  Humin,  was  a  curious  one,  and  suggested 
a  reason  for  the  great  variations  between  the  ana- 
lytical results  obtained  by  different  chemists  with 
peat.  Further,  while  the  Humic  acid  from  the 
sugars  and  that  from  peat  were  almost  identical  in 
appearance,  solubility  and  behaviour  to  alkalis, 
they  showed  striking  differences  in  composition. 
Neglecting  decimals,  the  analyses  of  the  two  acids 
gave — * 


Carbon. 

Hydrogen. 

Oxygen. 

Humic  Acid  from  sugar     .  . 
Humic  Acid  from  peat 

65  per  cent. 
54 

5  per  cent. 
5 

30  per  cent. 

38       „ 

The  authors  responsible  for  the  analysis  given  in 
this  table  concluded  that  there  must  be  structural 
*  Robertson,  Irvine,  and  Dobson. 


HUMUS  75 

differences  between  the  material  and  the  artificial 
Humic  acids.  Recent  work,  however,  done  by 
Baumann  in  1909  had  shown  that  freshly  precipi- 
tated natural  Humic  acid  possessed  colloidal*  prop- 
erties, and  especially  the  power  of  forming  adsorption 
compounds.  Now  these  compounds  can  be  removed 
without  much  difficulty,  and  it  seemed  possible  that 
the  differences  observed  between  natural  and  arti- 
ficial Humic  acids  might  be  due  to  impurities  which 
had  been  adsorbed  by  the  Humic  acid  in  the  peat, 
and  which  were  not  present  in  the  artificially  pro- 
duced acid  because  it  had  had  no  opportunity  of 
ever  becoming  contaminated.  It  will  be  remembered 
that  it  was  the  discrepancy  noted  between  the  weight 
of  the  Nitrogen  in  the  air  and  the  Nitrogen  prepared 
by  chemical  methods  which  led  Sir  William  Ramsay 
to  undertake  the  brilliant  series  of  researches  result- 
ing eventually  in  the  discovery  of  the  rare  gases  of 
the  atmosphere.  It  will  be  seen  later  that  the 
study  of  the  difference  between  natural  and  artificial 
humic  acids  has  led  to  conclusions  of  far  greater 
importance  than  had  been  suspected. 

Elaborate  means  were  taken  to  purify  the  natur- 
ally produced  Humic  acid.  Some  finely  divided 
peat  was  powdered  and  treated  with  4  per  cent. 
Hydrochloric  acid  until  all  soluble  salts  had  been 
extracted,  and  then  treated  with  5  per  cent.  Am- 
monia. The  filtered  Ammonia  solution  was  acidified 

*  A  colloid  is  a  substance  possessing  a  very  large  molecule, 
and,  unlike  most  inorganic  chemical  compounds,  is  unable  to 
pass  through  an  animal  membrane.  By  adsorption  is  meant 
the  power  possessed  by  colloids  of  holding  other  substances  not 
in  actual  combination  with  them,  but  in  a  very  close  association. 


76 


THE  SPIRIT  OF  THE  SOIL 


with  strong  Hydrochloric  acid,  and  a  flocculent 
brown  precipitate  obtained.  This  was  filtered  off, 
redissolved  in  ammonia,  reprecipitated,  and  washed. 
The  Humic  acid  so  obtained  was  divided  into  two 
portions.  The  first  was  dried  in  a  steam  oven  at 
100°  C.,  while  the  second  was  purified  by  boiling  for 
an  hour  under  a  reflux  condenser  with  absolute 
alcohol.  These  two  portions  were  analyzed,  and  the 
following  figures  were  obtained : 


Carbon. 

Hydrogen. 

Oxygen. 

Natural  Humic  Acid 
Natural  Humic  Acid,  after 
extraction  with  alcohol.  . 

48-64 
60-37 

4'55 
5'39 

46-81 
34-24 

It  will  be  noticed  that  after  purification  with 
alcohol  the  natural  Humic  acid  was  closely  com- 
parable with  that  obtained  from  Dextrose,  as  can 
be  seen  from  the  table : 


Carbon. 

Hydrogen. 

Oxygen. 

Artificial  Humic  Acid 
Natural  Humic  Acid  (puri- 
fied           .  .          .... 

60-74 
60-37 

5-13 
5'39 

34-13 
34-24 

This  does  not  mean  that  a  real  formula  can  be 
written  for  Humic  acid,  for  it  is  well  known  that  the 
Carbon  content  of  Humic  acid  does  vary  with  the 
substances  from  which  it  has  been  prepared,  but  it 
emphasizes  that  a  very  close  similarity  exists  between 


HUMUS  77 

the  Humic  acid  obtained  from  peat  and  one  of  the 
Humic  acids  artificially  prepared. 

Now  in  the  ordinary  decomposition  of  cellulose  it 
cannot  be  expected  that  Hydrochloric  acid  would  be 
present,  but  as  a  result  of  decomposition  a  large 
number  of  organic  acids  would  naturally  be  formed, 
and  tests  carried  out  with  Lactic,  Acetic,  Propionic, 
Butyric,  Citric,  Tartaric,  and  Oxalic  acids  on 
Sucrose,  Dextrose,  and  Laevulose,  all  showed  that 
the  sugars  or  carbohydrates  went  through  the  same 
colour  changes  as  had  been  observed  with  Hydro- 
chloric acid,  and  gave  rise  both  to  Humic  acid  and 
Humin.  In  other  words,  it  was  demonstrated  that 
it  was  reasonable  to  suppose  that  the  natural  process 
by  which  Humic  acid  and  the  Humin  were  formed  in 
peat  from  carbohydrates  had  been  successfully 
imitated  in  the  laboratory. 

While  this  work  was  in  progress  some  interesting 
results  were  obtained  merely  by  the  heating  of 
sugar,  which  are  perhaps  worth  noting  here,  because 
they  may  help  to  give  a  clear  idea  as  to  the  nature 
of  Humic  acid  and  Humin.  It  has  long  been  known 
that  Sucrose  fuses  at  a  temperature  of  160°  C.,  and 
is  converted  into  a  mixture  of  Dextrose  and  Laevu- 
lose.  If  the  temperature  is  raised  to  190°  C.  it  yields 
a  substance  similar  to  the  caramel  of  commerce, 
Caramelan,  and  at  higher  temperatures  it  blackens, 
becoming  carbonized.  When  Sucrose  was  heated  to 
220°  C.  four  distinct  groups  of  substances  were 
formed. 

(i)  Water-soluble  caramelan;  (2)  a  water  soluble 
substance  precipitated  as  fine  particles  by  Hydro* 


78  THE  SPIRIT  OF  THE  SOIL 

chloric  acid;  (3)  an  alkali-soluble  substance  giving 
the  typical  flocculent  precipitate  of  Humic  acid  when 
treated  with  Hydrochloric  acid;  and  (4)  a  black 
residue  insoluble  in  water  and  alkalies,  and  giving 
the  typical  Humin  reactions.  Curious  differences 
were  found  to  occur  when  Dextrose  and  Laevulose 
were  similarly  treated,  but  these  are  points  of  detail 
that  hardly  concern  us  here.  The  points  to  which 
I  would  call  attention  are — (i)  that  the  heat -formed 
Humic  acids  differ  from  the  acid-formed  Humic  acids, 
in  that  on  being  dried  in  a  water-bath  at  100°  C. 
they  are  no  longer  soluble  in  dilute  alkali  solution, 
but  are  only  rendered  soluble  on  fusion  with 
caustic  potash  or  soda;  (2)  that  by  heating  or 
by  treating  with  acid  the  change  to  Humin  is 
via  Humic  acid;  and  (3)  that  in  both  cases  the 
general  effect  of  the  treatment  is,  as  in  Nature,  to 
take  the  elements  of  water  out  of  the  molecule  of 
carbohydrate. 

Plant  tissues  consist  chiefly  of  carbohydrates  and 
proteins.  The  latter  are  of  varied  composition,  but 
consist  of  Carbon,  Hydrogen,  Oxygen,  and  Nitrogen 
in  combination,  and  the  Hydrogen  and  Oxygen  may 
or  may  not  be  in  the  proportions  necessary  to  form 
water.  Similar  tests  to  those  made  on  sugar  have 
been  carried  out  with  the  proteins,  and  it  has  been 
found  that  Humic  bodies  are  produced  only  in  so  far 
as  the  proteins  contain  carbohydrate.  For  instance, 
while  a  gramme  of  Mucin,  which  contains  carbo- 
hydrate, on  boiling  for  eight  hours  with  a  7*5  per 
cent,  solution  of  Hydrochloric  acid,  yielded 
0*028  gramme  of  Humic  acid,  no  Humic  acid  was 


HUMUS  79 

formed  either  with  Tyrosine  or  Asparagine  which 
contain  no  carbohydrates. 

It  is  to  some  extent  on  the  basis  of  the  above 
experiments  that  Professor  Bottomley  has  estab- 
lished his  method  for  introducing  bacteria  into  the 
soil.  In  his  paper  in  the  Biochemical  Journal  he 
drew  the  following  conclusions,  which  in  view  of  their 
important  bearing  on  the  subject  of  this  book  I  am 
quoting  textually: 

'  The  general  result  of  the  investigation  so  far," 
he  writes,  "  has  been  to  indicate  that  carbohydrates 
generally  and  certain  sugars  in  particular  pass 
through  a  regular  series  of  changes  when  submitted 
to  the  reactions  described.  It  was  also  found  that 
air-dried  sphagnum  moss  is  readily  acted  on  by 
acids,  with  the  formation  of  a  brown,  peat-like  mass 
from  which  Humic  acid  can  be  extracted. 

"  One  hundred  grammes  of  air -dried  sphagnum 
moss,  when  boiled  for  twenty-four  hours  with  5  per 
cent,  solutions  of  Hydrochloric,  Oxalic,  and  Lactic 
acids  respectively,  yielded  the  following  results : 

Humic  Acid. 
Hydrochloric  Acid     . .          . .      11*7  grammes. 

Oxalic  Acid     . .          . .          . .        2-3         ,, 

Lactic  Acid     ..          ..          ..        1*8         ,, 

"  The  humic  substances  comprising  the  Humic 
acid  and  Humin  groups  probably  pass  through  a 
series  of  changes  characterized  by  a  progressive 
increase  of  their  Carbon  content.  In  ordinary 
cultivated  soils  these  changes  cannot  be  traced, 
owing  to  the  constant  addition  of  fresh  organic 
matter  and  cultural  operations,  but  in  peat  beds, 


8o 


THE  SPIRIT  OF  THE  SOIL 


where  the  deposits  remain  undisturbed  for  many 
years,  the  stages  are  indicated  by  the  increasing 
Carbon  content  of  the  Humus  from  varying  depths. 
This  was  shown  by  Detmer  (1871),  who  gives  the 
following  figures : 


Carbon. 

Hydrogen. 

Oxygen. 

Light  brown  peat,  surface.  . 

52-14 

7'°3 

40-19 

Brown  peat,  i  foot.  . 

57'75 

5H3 

36-02 

Dark  peat,  7  feet 

62-02 

5*21 

30-67 

Black  peat,  14  feet.  . 

64*07 

5-01 

26-87 

"  Thus,  in  peat  bogs  the  carbohydrates  of  decaying 
organic  matter  may  possibly  pass  through  changes 
very  similar  to  those  observed  when  sugar  is  heated 
to  a  high  temperature — Sugar,  Caramelan,  Humic 
acid,  Humin,  and  finally  Carbonization  (peat  coal). 
The  fact  established  by  van  Bemmelen  (1900)  that 
Humic  acid  is  a  colloid  body,  which  has  the  property 
of  uniting  with  certain  radicles,  explains  the  various 
empirical  formulae  ascribed  to  Humic  acid,  and  the 
complex  nature  of  Humus  in  general.  But  under- 
lying this  complexity  there  is  the  possibility  of 
finding  in  the  series  of  sugar  changes  described  above 
two  fairly  definite  groups  of  substances,  which  serve 
as  a  basis  for  Humus  formation,  the  Humic  group 
gradually  merging  into  the  Humin  group." 


CHAPTER  VII 

BACTERIZED  PEAT:  ITS  PREPARATION  AND  GENERAL 
PROPERTIES 

Need  for  a  mixed  culture — Why  peat  was  used  as  a  medium — 
Other  possible  media — Decomposition  of  peat  by  aerobic 
bacteria — Superiority  of  artificial  over  natural  methods — 
Effects  of  decomposition — A  simple  experiment — Treated 
peat  contains  fifty  times  as  much  plant  food  as  stable 
manure — Peat  the  ideal  medium — The  aerobic  bacteria — 
Sterilizing  the  peat — Bacillus  radicicola,  Clostridium  pas-- 
teurianum,  and  Azotobacter — Conditions  of  growth — Symbi- 
otic relationships — Inoculating  the  peat — Why  the  soil 
should  benefit — Effect  of  nitrogen  fixation — Influence  on 
phosphates  and  potash — Accessory  food  bodies — Claims 
advanced  on  behalf  of  humogen. 

A  CONCLUSION  of  supreme  importance  was  reached 
as  a  result  of  the  experiments  made  in  the  Botanical 
Laboratories  of  King's  College  on  Bacillus  radicicola, 
the  micro-organism  responsible  for  the  fixation  of 
nitrogen  in  connection  with  leguminous  plants.  The 
discovery  had  been  made  that  the  bacillus,  when 
mixed  with  soil  and  dried,  was  able  to  retain  its 
vitality  unimpaired  certainly  for  a  considerable 
number  of  months,  and  in  favourable  conditions  for 
at  least  as  long  as  three  years.  Unquestionably 
soil,  for  the  introduction  of  the  bacillus,  was  a 
medium  vastly  superior  to  the  cotton  used  in 
America.  In  a  previous  chapter  I  have  attempted 

81  6 


82  THE  SPIRIT  OF  THE  SOIL 

to  show  why  it  was  that  in  several  instances  the 
culture  gave  negative  results  when  applied  to  the 
land.  The  difficulties  met  with  were  not  insuperable, 
but  as  the  experiments  continued  it  became  evident 
that  however  successful  a  leguminous  culture  might 
prove,  it  could  never  yield  more  than  a  fraction  of 
the  results  that  might  fairly  be  expected  if  bacterial 
inoculation  were  practised  from  a  broader  outlook. 
It  was  realized  that  Bacillus  radicicola  was  only 
one  of  several  organisms  connected  with  the  work 
of  changing  into  nitrogenous  plant  food  the  nitrogen 
present  in  the  air  circulating  from  the  atmosphere 
to  the  soil,  and  that  the  full  benefit  of  soil  inoculation 
could  only  be  obtained  by  supplying  to  the  soil  a 
mixed  culture  which  would  contain  the  various 
groups  of  bacteria  acting  in  different  ways  for 
the  common  end  of  supplying  nitrogenous  food  in 
soluble  form — that  is,  in  a  form  in  which  it  can  be 
utilized  by  plants. 

Chance  to  some  extent  decided  the  selection  of 
peat  as  a  medium  for  the  purpose.  As  a  matter  of 
fact,  however,  there  was  not  a  large  option.  Some 
substance  was  required  that  had  or  could  be  made 
to  yield  a  high  percentage  of  soluble  humus,  for  it 
was  known  that  it  was  on  this  that  the  bacteria  had 
to  rely  for  their  food.  Farmyard  manure  was  a 
possible  medium.  The  supply  of  it,  however,  was 
diminishing;  it  was,  and  must  always  remain,  un- 
pleasant to  handle,  and  it  was  objectionable  because 
of  the  host  of  mixed  organisms  it  was  bound  to 
contain.  Leaf  mould  was  objectionable  on  most  of 
the  same  grounds,  and  had  the  further  disadvantage 


BACTERIZED  PEAT  83 

of  being  very  bulky  to  handle  if  it  was  purchased 
raw,  and  of  being  very  costly  and  difficult  to  obtain 
in  bulk  if  it  was  to  be  delivered  already  rotted.  In 
peat  there  was  a  substance  rich  in  humus-forming 
material,  available  in  indefinitely  large  quantities, 
cheap,  pleasant  to  handle,  highly  concentrated  as  a 
result  of  natural  processes  continued  over  immense 
periods  of  time,  varying  in  composition  over  a  wide 
range,  and  for  practical  purposes  sterile. 

In  its  raw  state  peat  contains  practically  no  soluble 
humus.  The  nature  of  its  deposition  has  been  such 
that  free  access  of  air  has  been  prevented,  and  its 
Carbon  compounds  (the  carbohydrate,  protein,  etc.) 
have  only  slowly  and  partially  decomposed.  In- 
stead of  the  neutral  or  alkaline  humus  required  as 
food  both  by  plants  and  bacteria,  acids  have  been 
formed,  and  the  peat  is  unable  to  support  the  life 
either  of  ordinary  plants  or  of  nitrogen-fixing 
organisms.  If  the  peat,  however,  is  left  exposed  for 
a  considerable  period,  such  as  two  years,  for  instance, 
the  long-delayed  change  that  occurs  in  the  case 
of  vegetable  matter  to  which  there  is  free  access 
of  air  readily  takes  place  Carbon  dioxide  and 
Ammonia  are  formed  freely  as  a  result  of  the  action 
of  aerobic  bacteria,  and  the  peat  slowly  loses  its  acid 
character.  Soluble  humus  accumulates  to  a  con- 
siderable extent  in  the  form  of  Ammonium  humate, 
and  the  peat  which  was  valueless  as  a  plant  food  now 
contains  available  nitrogen  compounds  As  with 
most  other  natural  changes,  so  with  this,  it  is  possible 
in  the  laboratory,  as  in  the  factory,  greatly  to 
accelerate  it.  Despite  the  ill-informed  attitude 


84  THE  SPIRIT  OF  THE  SOIL 

usually  adopted,  a  laboratory-performed  change  is 
frequently  more  effective  for  a  given  purpose  than 
one  carried  out  under  natural  conditions.  In  the 
present  case,  for  instance,  if  the  peat  were  simply 
thrown  upon  sandy  soil,  enormous  quantities  of  it 
would  be  lost.  Much  of  the  valuable  soluble  humus 
would  be  leached  out  by  rain,  and  pass  deep  into  the 
sand,  or  be  wasted  so  far  as  the  farmer  is  concerned 
by  being  carried  off  in  the  drains.  In  the  laboratory 
and  factory,  however,  it  is  a  simple  matter  to  control 
the  air-supply  and  the  temperature  so  as  to  give 
the  aerobic  bacteria  the  conditions  under  which  they 
can  work  best.  Only  the  inevitable  amount  of 
Carbon  dioxide  is  given  off  and  wasted.  The  process 
throughout  the  mass  is  homogeneous,  and  the 
reaction  carried  to  the  exact  conclusion  desired. 

In  such  conditions  the  results  obtained  are  amaz- 
ing. In  this  connection  there  can  be  no  question 
as  to  the  result,  for  it  can  be  tested  as  often  as  the 
observer  cares  with  the  greatest  ease  in  any  labora- 
tory, no  elaborate  appliances  or  delay  being  involved. 
All  that  is  required  is  half  a  dozen  test-tubes,  a 
couple  of  filters,  and  a  little  Hydrochloric  acid, 
some  well-rotted  stable  manure,  and  samples  of 
treated  and  untreated  peat.  The  value  of  the 
rotted  stable  manure  lies  in  its  soluble  content,  and 
the  amount  of  it  is  easily  gauged  approximately  by 
the  eye  and  accurately  by  the  balance.  Supposing 
that  equal  weights  of  rotted  stable  manure,  raw 
peat,  and  treated  peat  are  taken,  well  steeped  with 
equal  volumes  of  water  and  filtered,  the  liquid  from 
the  untreated  peat  is  found  to  be  almost  colourless, 


BACTERIZED  PEAT  85 

that  from  the  stable  manure  is  a  lightish  brown, 
while  that  from  the  treated  peat  is  so  concentrated 
that  it  has  the  appearance  of  being  black.  In  other 
words,  the  water  extract  of  untreated  peat  contains 
only  traces  of  soluble  humus,  that  from  stable 
manure — one  of  the  best,  if  not  the  best,  ordinary 
source  of  humus — contains  relatively  little,  while 
that  obtained  from  treated  peat  is  extremely  rich  in 
the  substance.  Supposing  now  that  these  three 
tubes  are  left  standing  for  purposes  of  comparison 
and  the  experiment  is  repeated,  we  have,  by  con- 
tinuing it  a  stage  farther,  a  very  simple  means  of 
getting  a  more  precise  measure  of  the  difference 
between  our  three  samples.  By  adding  Hydro- 
chloric acid  to  the  filtered  liquids  the  soluble  humus, 
chiefly  Ammonium  humate,  makes  its  appearance  in 
insoluble  form  as  a  brown  flocculent  precipitate  of 
Humic  acid.  When  Hydrochloric  acid  is  added  to 
the  water  extract  of  the  untreated  peat  scarcely  any 
precipitate  appears.  When  it  is  added  to  the  water 
extract  of  the  manure  a  precipitate  forms  that  may 
settle  down  to  occupy  J-  or  £  inch  of  the  test-tubes, 
but  when  the  acid  is  added  to  the  water  extract  of 
the  treated  peat  a  closely  compacted  precipitate 
results  that  may  be  as  much  as  6  or  8  inches  in  depth. 
To  get  an  exact  measure  of  the  food  values  of  the 
three  substances  it  is  only  necessary  to  filter  off 
these  precipitates,  to  dry  and  weigh  them.  Experi- 
ment has  shown  that  the  untreated  peat  gives  almost 
zero  as  its  value,  the  manure  a  unit  weight  and  the 
treated  peat  as  much  as  fifty  or  eighty  times  that 
obtained  from  the  manure.  The  following  are  the 


86 


THE  SPIRIT  OF  THE  SOIL 


actual  figures  of  one  of  a  score  of  experiments  that 
have  been  done  somewhat  on  these  lines,  only  on  a 
more  elaborate  scale.  It  shows  the  enormous  pre- 
ponderance of  treated  peat  in  available  nitrogenous 
plant  food. 


Soluble 

Soluble 

Total 

Humate. 

Nitrogen. 

Nitrogen. 

Raw  peat 

0-028 

0-214 

1-267 

Bacterized  peat 

I5'i94 

2-694 

4-310 

Garden  soil 

0*012 

0-026 

0-427 

Fresh  stable  manure  .  . 

0-433 

0-291 

2'533 

Well-rotted    stable 

manure 

1-460 

0-439 

2-848 

One-year-old  peat-moss 

litter  manure 

1-050 

0-826 

2-587 

If  the  object  of  the  experiments  undertaken  at  the 
Botanical  Laboratories  of  King's  College  had  been 
merely  to  find  some  new  source  of  manure  to  replace 
the  supplies  of  stable  manure,  which  both  market 
gardeners  and  agriculturists  know  are  year  by  year 
steadily  shrinking,  the  successful  conversion  of 
insoluble  peat  into  a  material  rich  in  soluble  plant 
food  comparable  in  value,  but  far  less  bulky  than 
that  obtained  in  stable  manure,  would  have  been  a 
notable  achievement.  It  is  true  that  there  would 
have  been  nothing  startling  in  the  idea  that  it  was 
possible  by  means  of  the  decomposition  bacteria  to 
speed  up  the  natural  process  which  was  known  to 
occur  slowly  in  peat,  and  thus  secure  a  valuable 
fertilizer  for  the  land.  It  is  true  also  that  the 
chemist  has  been  perfectly  well  aware  that  the  same 


BACTERIZED  PEAT  87 

change  can  be  effected  even  more  quickly  than  with 
bacteria  by  treating  the  raw  peat  with  alkalies,  but 
so  far  it  had  not  occurred  to  anyone  that  peat  could 
be  valuable  as  a  manure,  except  when  it  had  been 
well  rotted  by  natural  means.  Farmers  and  horti- 
culturists would  have  probably  long  rested  content 
with  buying  the  peat  used  in  stables  as  bedding,  and 
storing  it  up  to  rot  into  good  condition,  though,  as 
has  been  done  in  practice,  they  could  have  hastened 
the  process  by  mixing  it  with  lime. 

The  aim  of  those  working  at  the  problem,  how- 
ever, was  not  to  discover  a  fertilizer,  but  to  find  a 
medium  in  which  the  bacteria  connected  with  the 
fixation  of  nitrogen  could  be  cultivated  and  put  on 
the  land.  In  the  peat  treated  with  aerobic  bacteria 
they  found  such  a  medium,  which  was  far  superior 
to  anything  they  had  hoped  for.  When  once  the  peat 
has  been  treated  with  these  bacteria,  from  between 
20  to  25  per  cent,  of  it  is  available  as  soluble  plant 
food.  To  effect  the  change  all  that  is  necessary  is 
then  to  keep  the  peat  moistened  at  a  temperature  of 
26°  C.  (79°  F.)  for  about  a  week.  Steam  can  then 
be  forced  through  the  mass  for  as  long  as  is  desirable 
to  insure  that  all  organisms,  bacterial  or  other,  have 
been  destroyed,  and  the  result  is  a  sterile  medium, 
neutral  or  slightly  alkaline,  and  suitable  for  the 
cultivation  either  of  plants  or  of  bacteria. 

Once  a  suitable  medium  had  been  found  for  the 
growth  of  Nitrogen-fixing  organisms,  the  question  to 
be  settled  was  what  bacteria  could  best  be  utilized 
for  the  purpose  in  view.  As  has  been  seen  in  earlier 
chapters,  if  the  best  obtainable  results  were  to  be 


88  THE  SPIRIT  OF  THE  SOIL 

gained,  it  was  necessary  to  include  two  groups — the 
Bacillus  radicicola  group,  which  acts  only  in  associa- 
tion with  leguminous  plants,  and  the  other  group 
or  groups  that  were  able  to  fix  Nitrogen  while  they 
remained  free -living  in  the  soil.  As  regards  the 
radicicola  group  enough  has  already  been  said, 
except  for  the  statement  that  in  the  specially 
treated  peat  the  bacillus  found  a  material  better 
suited  for  its  needs  than  the  old  form  of  culture. 
There  was  no  longer  any  need  for  the  farmer  to 
dissolve  up  the  materials  supplied  him,  and  grow 
the  organisms  for  himself  in  home-made  apparatus 
with  temperature  and  other  conditions  quite  un- 
satisfactory for  the  process.  He  had  only  to  spread 
the  material  on  the  land  or  to  mix  it  with  his  seed, 
or  if  he  desired  it  in  liquid  form  he  could  extract  the 
peat  easily  with  water,  and  use  the  resulting  liquid 
to  water  the  roots  of  his  crop. 

Of  the  other  organisms  connected  with  Nitrogen- 
fixation  it  is  necessary  now  to  write  in  rather  greater 
detail.  Experiment  has  shown  that  just  as  land  on 
which  leguminous  crops  are  grown  becomes  richer 
in  Nitrogen,  so,  too,  there  may  be  an  increase  of  the 
Nitrogen  content  of  the  soil  in  cases  where  the  ground 
has  been  left  bare  of  vegetation.  In  such  circum- 
stances the  increase  will  be  comparatively  slow,  but 
at  Rothamsted  it  has  been  observed  to  increase  in  a 
year  by  as  much  as  25  pounds  an  acre.  There  are 
two  groups  of  bacteria  by  the  aid  of  which  the 
Nitrogen  circulating  in  the  soil  air  can  be  changed 
into  forms  of  nitrogenous  plant  food.  The  first  is 
anaerobic,  working  only  in  the  absence  of  Oxygen ; 


BACTERIZED  PEAT  89 

and  the  second  aerobic,  working  in  the  presence  of 
Oxygen.  The  former  of  these  bacterial  groups  was 
first  described  by  Winogradsky  in  1893,  and  was 
named  by  him  Clostridium  pasteurianum.  It  is  a 
small  rod-shaped  organism,  and  can  readily  be 
grown  in  solutions  containing  the  requisite  organic 
food,  such  as  sugar  and  mineral  salts.  But  nitrog- 
enous material  must  not  be  present.  In  such  cir- 
cumstances, if  Oxygen  is  absent,  it  develops  rapidly. 
It  can  even  grow  in  the  presence  of  Oxygen,  provided 
other  bacteria  are  mixed  with  it  to  take  up  the 
Oxygen  from  the  culture.  After  growing  for  a  few 
days  there  is  no  difficulty  in  showing  that  the 
bacteria  have  added  appreciable  quantities  of  com- 
bined Nitrogen  to  the  medium  in  which  they  have 
been  developing. 

Several  bacterial  groups  that  are  capable  of  fixing 
Nitrogen  in  the  presence  of  Oxygen  have  been 
isolated.  In  1901  Beyerinck  described  two  species, 
Azotobacter  chroococcum  and  Azotobacter  agilis.  Three 
additional  species  have  since  been  described  by  Dr. 
Lipman  of  the  New  Jersey  Agricultural  Experiment 
Station.  For  the  development  of  these  bacteria  a 
good  supply  of  air  is  essential,  a  fact  that  goes  a  long 
way  towards  explaining  why  it  is  desirable  for  the 
ground  round  the  roots  of  plants  to  be  kept  well 
aerated.  A.  chroococcum,  the  type  with  which  we 
are  most  concerned,  is  an  egg-shaped  organism  with 
a  marked  tendency  to  form  agglomerations.  It 
requires  for  its  development  far  less  food  material 
than  is  needed  by  Clostridium,  and  flourishes  best 
in  soil  where  lime  is  abundant.  When  cultivated  by 


go  THE  SPIRIT  OF  THE  SOIL 

itself  a  slime  forms  round  it,  the  nitrogen  com- 
pounds either  composing  the  whole  of  the  slime  or 
constituting  a  large  portion  of  it.  It  appears  to  be 
able  not  merely  to  fix  atmospheric  Nitrogen,  but  also 
to  transform  nitrogenous  bodies  present  in  the  soil 
that  are  unsuitable  for  plant  food  into  available 
nitrogenous  foodstuffs.  Curiously  enough,  like 
radicicola,  Azotobacter  very  readily  enters  into  some 
sort  of  symbiotic  relationships.  Thus  it  is  fre- 
quently found  living  in  association  with  green  algae. 
The  association  of  certain  other  bacteria  in  some 
way  as  yet  not  understood  appears  to  increase  its 
power  for  fixing  nitrogen.  Thus,  while  Azotobacter 
vinelandii  is  able  to  fix  more  nitrogen  than  Azoto- 
bacter beyerinckii,  the  output  of  the  latter  can  equal 
that  of  the  former  if  a  certain  other  small  bacterium 
is  present.  Commenting  on  this  remarkable  fact, 
Dr.  Lipman  writes :  "  In  what  manner  the  Azotobacter 
are  favoured  by  the  accompanying  organisms  is  not 
known.  It  is  likely,  however,  that  the  latter  use  up 
much  of  the  Nitrogen  fixed  by  the  Azotobacter,  and 
that  these  are  therefore  compelled  to  increase  their 
activities. 5? 

The  importance  of  the  fact  in  relation  to  bacterized 
peat  would  seem  to  be  considerable.  When  Azoto- 
bacter chroococcnm  is  grown  together  with  Bacillus 
radicicola,  Nitrogen  fixation  proceeds  more  satis- 
factorily and  in  greater  amount  than  if  the  two 
organisms  are  grown  separately.  The  character- 
istic slime  seen  round  Azotobacter  is  no  longer  ap- 
parent, but  long-continued  experiment  leaves  no 
doubt  but  that  there  is  something  in  the  nature  of 


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BACTERIZED  PEAT  91 

symbiosis  between  the  two  organisms,  and  that  the 
work  of  both  is  facilitated  by  the  co-operation. 

We  are  in  a  position  now  to  appreciate  the  second 
and  concluding  stage  in  the  production  of  bacterized 
peat.  The  treated  sterilized  peat,  rich  in  organic 
material  that  the  bacteria  are  able  to  utilize,  receives 
a  mixed  culture  of  Bacillus  radicicola  and  Azotobacter 
chroococcum.  The  bacteria,  being  at  a  temperature 
best  suited  to  their  growth  and  with  an  abundant 
supply  of  the  food  material  that  they  require, 
multiply  rapidly  and  permeate  the  mass  of  the  peat. 
When  the  whole  peat  mass  is  saturated,  the  action 
is  stopped  by  drying  the  peat,  and  the  material  is 
ready  to  be  applied  to  the  seed  or  to  the  soil. 

From  what  we  have  already  seen,  there  are  three 
ways  in  which  the  soil  might  be  expected  to  derive 
benefit  from  the  application  of  the  peat.  In  the 
first  instance,  the  richness  of  the  peat  in  soluble 
humus  should  increase  the  richness  of  the  soil  from 
the  point  of  view  of  the  food  elements  it  contains. 
Secondly,  if  leguminous  plants  are  present,  they 
should  derive  special  benefit  from  the  fact  that  the 
ground  is  being  inoculated  with  the  bacteria  neces- 
sary for  the  infection  of  their  roots  and  the  resulting 
fixation  of  Nitrogen.  Lastly,  whatever  the  plants 
grown,  the  soil  should  become  enriched  in  nitrog- 
enous foodstuffs  available  for  the  plants,  because 
the  bacteria  necessary  for  taking  Nitrogen  from  the 
air  in  the  soil  and  for  transforming  it  into  nitrog- 
enous food  material  have  been  added  to  the  soil 
and  supplied  with  the  exact  foods  which  they  require 
for  healthy  growth.  So  much  for  what  was 


92  THE  SPIRIT  OF  THE  SOIL 

expected.  In  a  later  chapter  dealing  with  the  results 
obtained  from  the  use  of  the  peat  I  shall  have  to  come 
back  to  the  subject,  but  in  the  meantime  I  will  quote 
from  an  article  contributed  by  Professor  Bottomley 
to  the  Illustrated  London  News  a  short  paragraph 
describing  the  influence  of  the  treated  peat  on  the  soil 
as  observed  in  one  of  many  laboratory  experiments : 

'  When  ordinary  soil,"  he  wrote,  "  is  mixed  with 
this  inoculated  peat  there  is  a  marked  increase  in 
the  Nitrogen  content  of  the  soil  if  the  temperature 
be  suitable  for  the  growth  of  the  bacteria.  A  mix- 
ture of  9  ounces  of  soil  from  Rothamsted  and  i  ounce 
of  inoculated  peat,  incubated  at  26°  C.  (79°  F.)  for 
twenty-eight  days,  gave  an  increase  of  54  milli- 
grammes of  Nitrogen  per  100  grammes  of  soil — a 
gain  equivalent  to  a  dressing  of  28  cwt.  of  nitrate  of 
soda  per  acre,  if  the  increase  had  been  proportional 
throughout  an  acre  of  soil  3  inches  deep." 

In  the  last  chapter,  it  will  be  remembered,  some 
emphasis  was  laid  on  the  peculiar  colloidal  properties 
of  Humic  acid,  and  of  its  power  to  adsorb  materials 
from  the  surrounding  medium.  In  the  course  of 
experiments  with  the  peat  the  apparent  paradox 
has  been  noticed  that  the  peat  enriches  the  soil  in 
the  phosphates  available  for  plant  food  to  a  far 
greater  extent  than  can  be  explained  by  the  amount 
of  available  phosphate  in  its  substance.  That  it 
can  increase  the  amount  of  phosphate  actually 
present  is  obviously  impossible,  but  that  the  treated 
peat  itself  contains  available  phosphate  and  avail- 
able potash  seems  clearly  settled  by  such  experi- 
mental evidence  as  that  plants  have  been  grown  and 


BACTERIZED  PEAT  93 

have  flourished  in  sterilized  moss  that  has  had  no 
other  treatment  than  watering  with  the  water 
extract  of  treated  peat.  It  would  seem  possible 
that  these  substances  are  brought  into  solution,  it 
may  be  as  the  result  of  the  action  of  the  Carbon 
dioxide  liberated  during  the  breaking  down  of  the 
peat,  and  that  they  are  held  or  adsorbed  by  the 
humate  molecules  in  such  a  form  as  to  be  readily 
utilizable  when  they  are  required  by  the  plant.  This 
result  was,  of  course,  quite  unexpected,  and  is  a 
side  issue  to  the  main  object  of  the  research;  but 
the  value  of  peat  is  obviously  greatly  increased  if  a 
result  of  its  action  is  to  render  available  to  the 
plants  grown  in  soil  so  treated  two  substances 
that  are  only  second  in  importance  to  nitrogenous 
food  material,  phosphate  and  potash,  which  were 
previously  present  in  unavailable  form.  While  the 
exact  mechanism  of  the  change  remains  uncertain, 
the  fact  is  that  during  the  process  of  decomposition 
the  organic  matter  of  the  soil  combines  with  such 
bases  as  Potassium  and  Calcium  to  form  humates. 
In  the  words  of  Mr.  Alfred  Machen:  "  The  practical 
importance  of  this  change  lies  in  the  fact  that  by 
adding  animal  or  vegetable  matter  to  the  soil  we 
not  only  improve  the  mechanical  texture,  but  by 
providing  the  necessary  bacterial  food  and  stimulus 
we  unlock  and  make  available  the  insoluble  potash 
and  phosphates  of  the  soil,  and  give  them  to  the 
plants  in  the  form  required — viz.,  potassic  humate 
and  phospho-humates.  The  fact  that  (i)  plants 
feed  on  humate  compounds,  and  (2)  that  organic 
matter  broken  down  by  bacterial  activity  in  the  soil 


94  THE  SPIRIT  OF  THE  SOIL 

produces  humate  from  the  insoluble  potash  and 
phosphate  are  very  important,  for  they  point  out  a 
way  of  cheaply  converting  the  inert  plant  foods  of  the 
soil  into  more  active  and  available  forms.  Considera- 
tion of  these  facts  makes  it  understandable  why  the 
application  of  organic  manures  has  such  good  effects." 
In  the  course  of  experiments  made  with  bacterized 
peat  on  the  growth  of  plants  some  very  remarkable 
effects  were  noted.  The  plants  which  were  treated 
with  the  material  exhibited  a  characteristically 
marked  root  development,  they  frequently,  almost 
normally,  matured  at  an  earlier  stage,  and  they  were 
generally  more  robust  than  those  which  had  not 
received  the  bacterized  peat.  When  it  is  remem- 
bered that  these  plants  were  being  grown  against 
others  which  were  receiving  what  the  growers 
regarded  after  long  experience  as  the  fertilizers  best 
suited  to  their  requirements,  it  is  clear  that  the 
increased  vigour  of  the  plant  could  not  be  due  to  the 
organic  material  known  to  be  in  the  peat,  nor  to  the 
phosphates  and  potash  that  had  become  available, 
nor  even  to  the  lavish  supply  of  nitrogenous  foods 
derived  from  the  air.  The  hypothesis  was  formed 
that  the  treated  peat  might  perhaps  be  rich  in 
accessory  food  bodies  similar  to  the  vitamines  that 
in  recent  years  have  been  found  to  be  essential  to 
animal  growth.  Experiments  have  now  been  in 
progress  on  this  subject  for  over  two  years,  and  the 
accuracy  of  the  hypothesis  either  in  its  present  form, 
or  in  some  closely  similar  form,  may  be  regarded  as 
established.  As  the  subject  is  so  novel,  so  striking, 
and  of  such  fundamental  importance,  certainly  in 


BACTERIZED  PEAT  95 

connection  with  the  nutrition  of  plants,  and  perhaps 
also  so  far  as  the  treated  peat  is  concerned  in  con- 
nection with  the  nutrition  of  animals,  I  am  reserving 
it  for  a  special  chapter. 

To  conclude  the  present  chapter  it  may  perhaps  be 
convenient  to  the  reader  if  I  append  a  summarized 
statement  by  Mr.  Alfred  Machen,  who  has  been 
closely  associated  with  Professor  Bottomley  in  the 
later  stages  of  the  research,  as  to  the  claims  that  can 
be  made  on  behalf  of  bacterized  peat  or  humogen. 
It  appears  in  the  course  of  an  article  contributed  to 
the  Fruit,  Flower,  and  Vegetable  Trades  Journal  for 
June  of  this  year,  and  is  as  follows : 

"  Manure  has  been  discovered  which  possesses  the 
following  remarkable  properties : 

i.  Humogen  is  an  entirely  organic  material 
(humus),  a  large  proportion  of  which  is  soluble 
ammonium  humate. 

"2.  It  directly  introduces  into  the  soil  the  Nitro- 
gen-fixing organisms,  and  provides  the  food  necessary 
for  their  rapid  multiplication. 

"3.  During  the  bacterial  decomposition  of  the 
peat  comparatively  large  quantities  of  '  accessory 
food  bodies  '  are  liberated.  These  bodies  enable  the 
plant  to  utilize  the  food  in  the  soil  by  stimulating  the 
natural  growth  activities. 

"4.  It  is  free  from  smell,  dust,  weed  seeds,  disease 
spores,  and  insect  pests,  and  is  clean  and  pleasant  to 
handle. 

''5.  An  ideal  and  complete  liquid  manure  is  made 
by  steeping  in  water.  So  efficient  is  this  liquid  that 
plants  will  actually  grow  in  it. 

"6.  The  soil  is  made  more  fertile  without  subse- 
quent dressing,  owing  to  the  continual  bacterial 
action." 


CHAPTER  VIII 

VITAMINES,   ACCESSORY  FOOD   BODIES  AND 
AUXIMONES 

Importance  of  accessory  food  bodies  —  The  perfect  physio- 
logical diet  —  Beriberi  and  milled  rice  —  Vordermann's 
contention  and  deficiency  diseases — Experimental  beri- 
beri in  fowls  —  Funk's  vitamines  —  Their  origin  —  Beri- 
beri vitamin es  and  scurvy  vitamines — Moore's  experi- 
ments on  growth — Accessory  food  bodies  and  bacterized 
peat  —  Rosenheim's  experiments  on  the  primula  —  Ex- 
traction of  accessory  food  bodies  from  peat — First  experi- 
ments on  wheat  seedlings — Effects  of  Silver  nitrate  and 
Phosphotungstic  acid  fractions  on  wheat — Water  culture 
experiments — The  same  with  elimination  of  seeds — Funk's 
vitamines  compared  with  Hop  kins' s  accessory  food  bodies 
— Auximones — Tests  with  Azotobacter — A  soil  experiment 
showing  Nitrogen  fixation — Bacteria  as  a  test  for  auxi- 
mones  —  The  scum-forming  organisms  —  Sensitiveness  of 
the  test — Analogy  with  Hopkins's  accessory  food  bodies — 
Auximones  in  rotted  manure  —  Leguminous  plants  as 
sources  of  auximones — Nature  of  scum-forming  organisms 
— The  "  food  of  the  gods  " — An  experiment  with  chicks 
and  a  provisional  deduction — The  "  standard  bread  ' 
agitation. 

THE  discovery  of  accessory  food  bodies  has  been 
without  question  one  of  the  most  remarkable 
advances  of  modern  Biology.  It  is  rather  the 
fashion  nowadays  to  talk  of  recent  discoveries 
having  hurried  to  the  scrap-heap  the  work  of  earlier 
generations.  When  the  isolation  of  radium  aston- 

96 


ACCESSORY  FOOD  BODIES  97 

ished  the  chemists  and  physicists,  there  really  were 
people  in  plenty  who  believed  that  all  the  patient 
endeavours  of  150  years  had  gone  by  the  board. 
In  the  same  way  in  medicine,  while  we  say  with 
justice  that  the  knowledge  gained  of  bacteria  has 
revolutionized  the  science  and  art  of  medicine, 
many  of  us  are  inclined  to  forget  that  the  solid 
foundations  on  which  the  art  rested  in  the  fifties  still 
remain  established,  even  though  the  successful 
nature  of  modern  achievement  has  to  some  extent 
hidden  them  from  view. 

For  many  long  years  it  was  an  established 
principle  among  animal  physiologists  that  the  perfect 
physiological  diet  consisted  of  so  many  grammes  of 
carbohydrate,  so  many  grammes  of  fat,  and  so  many 
grammes  of  protein,  with  a  few  necessary  salts  in 
addition.  It  was  believed  that  by  increased  per- 
fection in  the  art  of  measurement  the  whole  of  an 
animal's  activities  could  be  expressed  in  the  form 
of  an  energy  equation,  reduced  for  purposes  of  con- 
venience to  terms  of  heat.  On  the  one  side  were 
placed  the  heat  units  or  calories  contained  in  the 
food;  the  other  side  of  the  equation  showed  how 
this  energy  had  been  spent,  and  consisted  of  such 
items  as  the  residual  energy  value  of  the  waste  pro- 
ducts of  the  body,  the  heat  dissipated  to  the  air 
through  the  lungs  and  skin,  the  heat  absorbed  to 
turn  liquids  into  gases,  the  energy  spent  in  work 
and  locomotion,  and  so  forth.  The  work  so  done 
was,  and  remains,  valuable,  but  all  the  time  physiolo- 
gists had  a  feeling  that  everything  could  not  be 
explained  by  a  consideration  of  energy  factors. 

7 


g8  THE  SPIRIT  OF  THE  SOIL 

Some  men,  as  they  do  still,  took  refuge  in  con- 
ceptions of  vitalism,  shelving  in  fact  the  problem  as 
insoluble;  others  are  pressing  on  in  search  of  fresh 
material  evidence  to  illuminate  what  remains 
obscure.  It  may  well  be  that  the  problem  of  the 
living  organism  will  never  be  solved  by  the  physiolo- 
gist, for  as  the  research  proceeds  fresh  factors  are 
continually  bringing  themselves  into  evidence,  and 
with  the  increase  of  knowledge  it  becomes  more  and 
more  possible  to  form  some  appreciation  of  the 
extent  of  the  unknown. 

It  was  through  researches  undertaken  on  disease 
that  the  physiologist  was  brought  to  recognize  the 
existence  and  importance  of  accessory  food  sub- 
stances. Both  experiment  and  observation  had 
long  ago  accustomed  him  to  the  idea  that  minute 
quantities  of  substance  might  have  astonishingly 
important  results  on  the  welfare  of  the  body. 
Cretinism,  with  all  the  disarrangement  of  growth 
and  function  associated  with  it,  had  been  proved  to 
be  conditioned  by  the  absence  of  the  excretions  of 
the  thyroid  gland.  Starling  and  others  had  been 
pressing  their  researches  to  elucidate  the  elaborate 
chemical  mechanism  by  which  the  conduct  of  the 
body  tissues  is  regulated,  and  the  blood  had  come 
to  be  regarded  no  longer  as  a  simple  liquid  in  which 
red  and  white  blood  corpuscles  floated  about  their 
business,  but  as  an  intensely  complex  aggregate  of 
chemical  substances,  some  of  which  were  necessary 
for  the  hourly  needs  of  the  body,  while  others  were 
present  there  on  the  bare  chance  of  the  emergency 
arising  that  they  were  designed  to  meet. 


ACCESSORY  FOOD  BODIES  99 

Since  the  year  1896,  when  Vordermann  put  for- 
ward the  theory  that  beriberi  occurred  after  the 
long-continued  use  of  milled  rice — that  is,  of  rice 
from  which  the  outer  layers  of  the  grain  had  been 
artificially  removed — a  whole  group  of  diseases  has 
come  to  be  recognized  under  the  common  class  name 
of  "  deficiency  diseases/'  They  comprise  beriberi, 
scurvy,  and  its  congeners,  pellagra,  and  possibly 
rickets,  tetany,  osteomalacia,  and  sprue.  Vorder- 
mann's  view  was  not  long  in  receiving  confirmation, 
and  the  further  fact  was  soon  noted  that  persons 
whose  diet  consisted  of  unmilled  rice — that  is,  of 
rice  which  retained  its  outer  layers — were  exempt 
from  the  disease.  The  more  exact  method  of 
experiment  was  at  once  introduced  to  supplement 
observation.  Eykman,  attempting  to  produce  the 
disease  in  fowls,  fed  some  birds  purely  on  polished 
rice.  They  rapidly  lost  weight  and  developed 
neuritis  (polyneuritis  gallinarum).  Birds  fed  on 
whole  grain  rice  developed  no  such  disease.  The 
outbreak  of  the  disease  was  prevented  by  adding  the 
rice-polishings  (the  pericarp  of  the  grain)  to  the  diet, 
and  even  when  the  disease  was  established  it  could 
be  cured  by  administering  a  water  extract  of  the 
rice-polishings.  It  had  in  fact  been  shown  experi- 
mentally how  the  disease  could  be  brought  on  in 
fowls,  and  also  how  it  could  be  cured. 

Casimir  Funk  then  attacked  the  problem  chemic- 
ally, and  after  a  series  of  investigations  he  succeeded 
in  isolating  a  substance  from  the  alcoholic  extract  of 
rice-polishings,  which  appeared  as  colourless,  needle- 
shaped  crystals,  and  was  markedly  valuable  for 


ioo  THE  SPIRIT  OF  THE  SOIL 

curing  experimental  beriberi.  Its  formula  is  not 
definitely  known,  but  it  is  a  nitrogenous  substance, 
appears  to  be  a  pyrimidine  base,  and  probably  exists 
in  food  as  a  constituent  of  nucleic  acid.  Of  this 
substance  Dr.  Watson-Wemyss,  in  an  article  on 
"  A  Summary  of  Recent  Work  on  Vitamines,"  pub- 
lished in  the  Edinburgh  Medical  Journal  for  last 
March,  writes: 

"  As  a  result  of  this  valuable  work,  the  prevention 
and  cure  of  beriberi  came  to  rest  for  the  first  time  on 
a  scientific  basis.  Funk's  vitamine  has  been  proved 
to  be  the  most  powerful  and  rapid  remedy  we 
possess  in  beriberi.  It  is  present  in  food  in  such 
minute  quantities  that  simple  dietetic  treatment  of 
the  disease  brings  about  recovery  very  slowly,  and 
the  difficulty  of  obtaining  isolated  vitamine,  together 
with  its  expense,  make  its  general  use  at  present 
impossible.  It  is  hoped  that  it  may  prove  possible 
to  produce  Funk's  vitamine  synthetically." 

Once  this  new  line  of  research  was  suggested  to 
workers,  it  was  soon  found  that  vitamines  were 
widely  distributed  both  in  the  animal  and  vegetable 
kingdom.  Yeast,  milk,  yolk  of  eggs,  meat,  wheat, 
oats,  and  barley,  have  all  been  shown  to  contain 
them.  They  are  not  identical  in  character.  While, 
for  instance,  dried  corn  only  contains  beriberi 
vitamine,  scurvy  vitamine  also  appears  as  soon  as 
the  corn  begins  to  germinate.  Fresh-growing  plants, 
potatoes,  juicy  fruits,  and  vegetables,  are  rich  in 
scurvy  vitamines,  but  they  disappear  on  drying  or 
on  heating  to  100°  C.  Beriberi  vitamine  resists 
drying,  and  is  also  more  resistant  to  heat.  A  point 
requiring  emphasis  at  this  stage  is  the  minute 


ACCESSORY  FOOD  BODIES  101 

quantity  of  vitamine  that  is  present.  In  rice,  for 
instance,  only  the  ten-thousandth  part  of  the  rice 
consists  of  vitamine,  a  fact  that  suggests  that  the 
action  of  vitamines  is  in  some  way  comparable  with 
that  of  hormones  and  the  secretions  of  the  ductless 
glands. 

It  has  long  been  recognized  that  scurvy  is  a  disease 
conditioned  by  the  absence  of  fresh  food,  and  that 
if  fresh  food  is  obtainable  the  disease  yields  rapidly 
to  treatment.  Sea  experience  of  long  standing 
has  proved  the  efficiency  of  lime-juice  in  its  treat- 
ment, and  Funk  has  shown  both  that  lime-juice  is 
rich  in  scurvy  vitamine,  and  that  the  acidity  in  its 
composition  helps  to  increase  its  stability.  While 
scurvy  and  beriberi  are  similar,  there  seems  to  be  no 
doubt  that  they  are  different  diseases,  caused  by  the 
absence  of  different  vitamines  from  the  diet,  for 
whereas  scurvy  vitamine  by  itself  can  prevent  both 
beriberi  and  scurvy,  beriberi  vitamine  will  prevent 
only  beriberi,  and  will  not  affect  scurvy. 

For  those  interested  in  the  subject  of  vitamines 
there  is  already  a  long  literature  available,  and  no 
useful  purpose  would  be  served  here  by  further 
considering  the  relation  between  vitamines  and 
other  diseases.  Reference,  however,  must  be  made 
to  the  experiments  conducted  by  Benjamin  Moore 
and  others,  on  the  relations  between  vitamines  and 
healthy  growth.  On  feeding  young  rats  with  a 
diet  of  white  bread  growth  was  very  soon  arrested, 
whereas  they  flourished  on  a  diet  of  wholemeal  bread. 
The  experiment  had  many  interesting  features. 
It  showed,  for  instance,  how  the  vitamine-starved 


102  THE  SPIRIT  OF  THE  SOIL 

animals  recovered  when  their  diet  of  white  bread 
was  replaced  by  wholemeal  bread.  To  describe  it 
in  detail  would  take  up  too  much  space,  and  to  do 
so  is  the  less  necessary  because  it  formed  the  basis 
of  the  campaign  instituted  a  few  years  ago  in  favour 
of  "  standard  bread."  The  fact  that  I  wish  to 
emphasize  is  that  vitamines  are  as  essential  to 
growth  as  they  are  to  health ;  in  fact  they  are  more 
so,  as  in  diet  where  they  are  abundant  the  normal 
rate  of  growth  is  stimulated.  So  much  is  this  the 
case  that  it  has  even  been  suggested  that  they  may 
be  responsible  for  tumour  growth,  and  that  the 
formation  of  tumours  might  be  checked  by  the 
elimination  from  the  diet  of  the  substances  exciting 
growth. 

In  the  course  of  the  experiments  made  with 
bacterized  peat  or  humogen  some  very  surprising 
results  were  obtained.  In  the  first  instance,  in  a 
whole  series  of  experiments  conducted  at  Kew 
Gardens  and  at  the  Chelsea  Physic  Garden  during 
the  summer  of  1913,  on  various  pot  plants — wheat, 
barley,  oats,  maize,  salvia,  fuchsia,  carnation, 
primula,  etc. — it  became  evident  that  the  bacterized 
peat  possessed  a  certain  growth-stimulating  property 
that  could  not  be  accounted  for  by  any  known 
manurial  constituents  present .  Further  experiments 
showed  that  the  stimulating  substance  was  soluble 
in  water  and  effective  in  very  minute  quantities. 
Dr.  Rosenheim  of  King's  College,  in  an  experiment 
with  seedlings  of  Primula  malacoides,  potted  up  in 
loam,  leaf  mould,  and  sand,  found  that  plants 
watered  twice  with  the  water  extract  of  only 


ACCESSORY  FOOD  BODIES  103 

o'i8  gramme  of  bacterized  peat  were  after  six  weeks' 
growth  double  the  size  of  similar  untreated  plants, 
and  it  was  noted  that  flower  production  and  root 
development  were  promoted  equally  with  increase 
of  foliage.  In  view  of  what  was  then  known  as  to 
the  effect  of  vitamines  on  the  growth  of  animals  and 
on  their  health,  it  was  decided  as  a  preliminary 
experiment  to  follow  the  method  adopted  by  Cooper 
and  Funk  for  the  isolation  of  beriberi  vitamine. 
A  considerable  quantity  of  bacterized  peat  was 
extracted  with  absolute  alcohol  in  a  shaking  machine 
for  three  hours,  and  the  extract  was  filtered  off  and 
evaporated  to  dryness  in  vacuo.  The  residue  was 
taken  up  in  distilled  water,  'filtered,  and  to  the  filtrate 
Sulphuric  acid  was  added  until  the  concentration  of 
the  latter  reached  5  per  cent.  A  slight  precipitate 
of  Humic  acid  was  filtered  off,  and  to  the  filtrate  an 
excess  of  a  30  per  cent,  solution  of  Phosphotungstic 
acid  was  added.  The  whole  was  then  left  to  stand 
overnight,  when  the  liquid  was  decanted  off  through 
a  filter,  the  precipitate  repeatedly  washed  with  a 
5  per  cent,  solution  of  Sulphuric  acid,  and  finally 
decomposed  with  an  excess  of  Baryta.  The  liquid 
was  filtered  off  from  the  precipitate  of  Barium 
phosphotungstate,  and  the  filtrate,  freed  from  the 
last  traces  of  Baryta  by  means  of  a  very  dilute 
solution  of  Sulphuric  acid,  was  evaporated  to  dryness 
in  vacuo.  From  7  kilogrammes  of  bacterized  peat 
the  amount  of  dry  substance  thus  obtained  amounted 
to  12*0096  grammes.  For  purposes  of  testing,  this 
dried  residue  was  dissolved  in  such  a  way  that  the 
amount  extracted  from  10  grammes  of  the  original 


104 


THE  SPIRIT  OF  THE  SOIL 


peat  should  be  contained  in  a  litre  of  water.  In 
other  words,  the  proportion  of  the  dry  Phospho- 
tungstic  acid  fraction  in  the  final  solution  employed 
consisted  of  17  parts  per  1,000,000. 

Wheat  seedlings  were  the  first  plants  selected  for 
trial.  Nine  pots  were  taken,  filled  with  sand,  and 
divided  into  groups  of  three.  Ten  wheat  seeds  were 
planted  in  each  pot.  Three  separate  solutions  were 
made  up.  Each  of  these  contained  Nitrogen,  Phos- 
phate, and  Potash  in  the  ratio  of  400,  200,  and 
1,200  parts  per  1,000,000  respectively.  The  first 
solution  was  then  left  as  such ;  to  the  second  was 
added  the  alcoholic  extract  from  10  grammes  of  peat 
per  litre  of  solution,  while  the  third  received  instead 
(in  addition,  of  course,  to  the  Ammonia,  Phosphate, 
and  Potash)  17  parts  per  1,000,000  of  the  dry  sub- 
stance obtained  from  the  Phosphotungstic  fraction. 
Each  week  after  sowing  each  pot  received  100  c.c. 
of  solution.  At  the  end  of  the  period  the  plants 
were  uprooted,  washed,  dried,  and  weighed.  The 
results  were  as  follow : 


Weight  of 

Increase 

Series. 

Thirty 

over 

Plants. 

Series  i. 

Grammes. 

Per  Cent. 

i  .  Complete  food  solution 

11-94 



2.  Complete  food  solution  plus  alco- 
holic solution  of  peat 

14-46 

2I-I 

3.  Complete  food  solution  plus  Phos- 

photungstic fraction 

I5'45 

29H 

This  experiment  indicated  clearly  that  the  sub- 
stance in  bacterized  peat,   which  had  proved  its 


ACCESSORY  FOOD  BODIES  105 

efficiency  in  stimulating  plant  growth,  was  also 
precipitated  by  Phosphotungstic  acid,  and  that  the 
Phosphotungstic  acid  fraction  was  quite  as  effective 
as  the  original  alcoholic  extract  of  the  peat.  Further, 
some  confirmation  was  given  to  the  hypothesis  that 
the  peat  contained  bodies  similar  in  action  to 
vitamines. 

Funk  found  that  on  treating  his  Phosphotungstic 
acid  fraction  with  Silver  nitrate  he  had  been  able  to 
obtain  his  vitamines  in  crystalline  form.  To  deter- 
mine, therefore,  how  far  the  growth  stimulant  in 
bacterized  peat  resembled  the  vitamines,  the  Phos- 
photungstic acid  fraction  of  the  peat  was  treated 
similarly.  It  was  decomposed  as  described  above 
with  Baryta,  and  to  the  filtrate  from  the  Barium 
salt  Silver  nitrate  was  added  until  no  further  pre- 
cipitate was  produced.  The  brownish  precipitate 
was  filtered  off,  well  washed,  suspended  in  dilute 
Sulphuric  acid,  and  decomposed  with  Sulphuretted 
hydrogen.  The  nitrate  from  the  Silver  sulphide 
was  then  exactly  neutralized  with  Baryta,  the  clear 
liquid  filtered  off  from  the  precipitate  of  Barium 
sulphate,  and  evaporated  to  dryness  in  vacuo.  The 
weight  of  dry  substance  obtained  from  the  Silver 
fraction  from  7  kilogrammes  of  bacterized  peat 
amounted  to  0-2452  gramme,  and  as  this  also  was 
made  up  into  a  solution  so  that  a  litre  of  it  should 
contain  the  silver  fraction  from  10  grammes  of 
peat,  the  solution  contained  the  Silver  fraction  to 
the  amount  of  0-35  part  per  1,000,000 — i.e.,  approxi- 
mately i  part  per  3,000,000. 

To  test  the  efficiency  of  this  Silver  extract  three 


io6 


THE  SPIRIT  OF  THE  SOIL 


series  of  trials  were  made.  Nine  pots  in  all  were 
taken,  and  15  grains  of  wheat  were  planted  in  each 
in  sand.  All  nine  pots  received  Ammonia,  Phos- 
phate, and  Potash,  as  in  the  previous  experiment. 
The  first  series  had  this  alone,  the  second  series  also 
received  some  17  per  1,000,000  solution  of  the 
Phosphotungstic  acid  extract,  while  the  third  was 
given  some  of  the  0*35  per  1,000,000  solution  of  the 
Silver  nitrate  extract.  As  before,  the  plants  were 
first  treated  a  week  after  planting,  and  then  each  pot 
received  100  c.c.  of  its  food  solution  once  a  week. 
At  the  end  of  the  seventh  week  the  results  after 
drying  were  as  follow : 


Gross 

Series. 

Weight 
of  Forty- 
Five 

Increase 
over 
Series  i. 

Dry 

Weight. 

Increase 
over 
Series  i. 

Plants. 

Grammes. 

Per  Cent. 

Grammes. 

Per  Cent. 

i.  Complete  food 

64'5 

— 

13-3480 

— 

2.  Complete   food 

96-8 

50 

16-3818 

22-7 

plus  Phospho- 

tungstic frac- 

tion 

3.  Complete   food 

96*5 

49-6 

15-7148 

17-7 

plus  Silver  ni- 

trate fraction 

As  this  experiment  showed  that  the  silver  nitrate 
extract  gave  results  comparable  with  those  obtained 
with  the  Phosphotungstic  acid  precipitate,  it  was 
decided  further  to  try  the  experiment  of  growing 
wheat  seedlings  in  water  culture.  Two  sets  of 
eighteen  similar  seedlings  were  selected,  each  set 
being  originally  of  equal  weight — 473  grammes. 


ACCESSORY  FOOD  BODIES 


107 


The  first  set  were  distributed  among  three  bottles, 
each  having  a  capacity  of  200  c.c.  The  bottles  were 
filled  with  physiologically  pure  water,  to  which  the 
pure  salts  necessary  for  Detmer's  nutrient  solution — 
Ammonia  400,  Phosphate  200,  and  Potash  1,220, 
parts  per  1,000,000 — were  added.  The  second  set 
were  grown  in  a  solution  precisely  similar,  except 
that  o'35  parts  per  1,000,000  of  the  Silver  nitrate 
fraction  of  treated  peat  extract  had  been  added. 
The  bottles  were  aerated  daily,  and  the  solutions 
changed  twice  a  week.  Every  sixteen  or  seventeen 
days  the  plants  were  removed,  dried,  and  weighed. 
The  results  obtained  were  as  follow : 


Series.* 

Weight  of  Sets  of  Eighteen 
Plants. 

Gain  or  Loss 
on  Original 
Weight. 

Grammes. 

Per  Cent. 

i.  Pure  food  solu- 

Original weight     .  .      4-73 



tion 

After  sixteen  days        5*42 

+  14-7 

After  further  seven-     5-29 

+  H-8 

teen  days 

Ditto           ..          ..      4-33 

-8-4 

2  .  Pure  food  solu- 

Original  weight     .  .      4*73 



tion   plus 

After  sixteen  days       5-57 

+  17-7 

Silver  nitrate 

After  further  seven-     6-65 

+  40-6 

fraction 

teen  days 

Ditto           .  .          .  .     7-33 

+  54*9 

The  distinction  between  these  two  experiments  is 
brought  out  strikingly  in  the  following  diagram, 
where  the  weights  of  the  two  series  of  plants  are 

*  The  poor  growth  of  the  seedlings  in  this  series  is  explained 
by  the  fact  that  the  experiment  was  made  early  in  the  year, 
when  the  plants  obtained  very  little  sunshine. 


io8 


THE  SPIRIT  OF  THE  SOIL 


plotted  against  time,  the  dotted  line  showing  the 
plants  that  had  no  Silver  extract,  and  the  unbroken 
line  those  which  received  the  extract: 


8-0 


7-0 


J6-o 


4-0, 


10      zo      30      -i.o 
Time    in   Ua.i;5 


This  experiment,  particularly  when  taken  in  con- 
junction with  the  previous  ones  and  others,  proves 
conclusively  that  bacterized  peat  contains  a  sub- 
stance or  substances  which  stimulate  the  growth  of 
the  plant  and  enable  it  to  utilize  the  normal  food 
constituents  supplied  to  it.  In  nature  the  need 
is  doubtless  supplied  by  the  decaying  organic 
matter  in  the  soil. 

As  has  been  pointed  out  above,  anti-scorbutic 
vitamine  is  not  present,  so  far  as  can  be  ascertained, 
in  dry  seeds,  but  it  makes  its  appearance  two  or 
three  days  after  the  young  roots  have  begun  to  show, 
and  extracts  from  them  have  proved  as  effective  as 


ACCESSORY  FOOD  BODIES 


109 


extracts  of  green  vegetables  in  the  treatment  of 
scurvy.  The  hypothesis  was  suggested  that  special 
growth  substances  were  formed  during  germination, 
which  enabled  the  young  embryo  to  utilize  the  food 
material  present  in  the  seed.  To  test  this  it  was 
decided  to  remove  the  source  of  these  growth  sub- 
stances by  cutting  off  the  seed  as  soon  as  possible 
after  germination,  as  in  that  case  the  addition  of 
food  substances  would  have  a  much  more  marked 
effect.  For  the  experiment  two  series  of  wheat 
seedlings  were  taken  at  a  rather  earlier  age  than  in 
the  previous  experiment.  Before  removal  of  the 
seeds  both  sets  weighed  3*97  grammes,  and  after 
removal  of  the  seeds  3*2  and  3*17  grammes  respect- 
ively. Both  were  fed  on  Detmer's  solution,  but  the 
second  set  also  received  Silver  nitrate  fraction 
exactly  as  before.  The  results,  which  in  this  case 
were  even  more  striking,  were  as  follow: 


Series. 

Weight  of  Sets  of  Eighteen 
Plants. 

Gain  or  Loss 
in  Weight. 

Grammes. 

Per  Cent. 

i.  Complete  food 

Original  weight     .  .     3-20 



solution 

Weight  after  sixteen     3*37 

+  5'3 

days 

After  further  seven-     3-20 

O'O 

teen  days 

After  further  seven-     2-85 

—  10-9 

teen  days 

2.  Complete  food 

Original  weight     ..      3-17 



solution  plus 

After  sixteen  days  .  .      3-63 

+  r4'5 

Silver  nitrate 

After  further  seven-     4-29 

+  35'3 

fraction 

teen  days 

After  further  seven-     5-05 

+  59'3 

teen  days 

no 


THE  SPIRIT  OF  THE  SOIL 


When  the  variation  in  weight  is  plotted  as  before 
against  time  in  days,  the  effect  of  the  Silver  nitrate 
extract  which,  it  will  be  remembered,  was  added  to 
the  extent  of  only  about  i  part  in  3,000,000,  is 
most  remarkably  emphasized.  As  before,  the  dotted 
line  represents  the  growth  of  the  plants  fed  on  pure 
culture,  the  unbroken  line  that  of  the  plants  supplied 
with  Silver  nitrate  extract  of  treated  peat. 


I 2fc 

~/\ 


3P       40 


10      20 

Time 


In  view  of  the  very  slight  increase  of  growth  made 
by  the  untreated  plants,  the  assumption  seems 
justified  that  during  germination  certain  substances 
are  developed  which  enable  the  embryo  to  utilize 
the  food  material  present  in  the  seed,  and  that  these 
substances  can  be  replaced  in  whole  or  in  part  by 
the  Silver  fraction  from  an  extract  of  bacterized 
peat. 


ACCESSORY  FOOD  BODIES  in 

As  we  shall  see  in  a  later  chapter,  these  experi- 
ments do  not  stand  alone.  They  are  confirmed  not 
only  by  other  experiments  definitely  undertaken  to 
test  the  effect  of  the  Phosphotungstic  and  Silver 
nitrate  fractions,  but  the  whole  series  of  the  experi- 
ments made  with  the  treated  peat  becomes  intelli- 
gible when  considered  in  relation  to  the  accessory 
food  bodies. 

In  describing  the  results  obtained  it  has  seemed 
simpler  so  far  to  draw  only  a  slight  distinction 
between  the  vitamines,  as  described  by  Funk,  and 
the  accessory  food  substances,  as  described  by 
Hopkins.  There  is  a  close  similarity  between  the 
two  classes  of  bodies,  in  that  both  are  prepared  by 
means  of  Phosphotungstic  acid  and  Silver  nitrate 
from  such  substances  as  the  husk  of  grain,  yeast, 
egg-yolk,  milk,  and  so  forth.  There  are,  however, 
certain  differences.  Thus,  for  instance,  whereas  the 
vitamines  of  Funk  appear  to  be  in  the  nature  of  a 
pyrimidine  base,  in  the  experiments  made  by  Hop- 
kins it  was  insisted  that  the  bodies  used  were  free 
from  amino-acids,  purine  and  pyrimidine  bases.  It 
should  be  noted  also  that,  like  Hopkins's  bodies,  the 
plant  accessory  substances  are  resistant  to  heat. 
This  is  shown  by  the  fact  that  after  the  Phospho- 
tungstic extract  from  bacterized  peat  had  been 
treated  in  an  autoclave  at  134°  C.  for  half  an  hour, 
it  still  gave  the  characteristic  scum  reaction  (vide 
later  this  chapter) .  At  present  analytical  difficulties 
make  it  unwise  to  dogmatize  on  this  point.  What 
has  to  be  emphasized  is  that  the  treated  peat  con- 
tains substances  which  are  able  to  promote  growth 


H2  THE  SPIRIT  OF  THE  SOIL 

on  lines  similar  to  those  promoted  both  by  the 
vitamines  of  Funk  and  the  accessory  food  bodies  of 
Hopkins.  And  it  should  also  be  stated  that,  in  the 
opinion  of  Professor  Bottomley  and  his  co-workers, 
the  substances  with  which  he  is  dealing  are  more 
closely  related  to  the  accessory  food  bodies  of 
Hopkins  than  to  the  vitamines  of  Funk. 

When  Professor  Bottomley  first  called  attention 
to  the  existence  of  these  substances  in  peat,  he 
stated  that  further  work  was  being  undertaken  with 
a  view  of  clearing  up  the  nature  of  the  substances 
involved,  and  of  defining  their  properties.  While 
the  present  volume  was  in  course  of  preparation  a 
further  paper  was  published  in  the  Proceedings  of  the 
Royal  Society,  and  in  it  he  describes  the  bodies  under 
the  new  term  of  auximones  (from  avgi/mos,  promoting 
growth) . 

While  the  experiments  described  above  were  very 
necessary  to  establish  conviction,  they  had  the  great 
drawback  that  long  periods  were  required  for  carry- 
ing them  out.  The  delay  involved  in  order  to  test 
whether  or  not  a  given  solution  contained  auximones 
was  considerable,  five  or  seven  weeks  being  required 
to  enable  the  plants  tested  to  grow  sufficiently  to 
put  the  matter  beyond  dispute.  It  is  clear  that 
there  would  be  an  immense  saving  of  time  if  the 
same  result  could  be  obtained  by  treating  rapidly 
growing  bacteria  with  the  substance,  and  further  it 
was  obviously  of  great  importance  from  the  stand- 
point of  the  main  research  to  know  what  influence, 
if  any,  the  auximones  had  on  the  growth  of  the 
nitrogen-fixing  organisms.  Azotobacter  chroococcum 


ACCESSORY  FOOD  BODIES  113 

was  used  for  the  experiment.  Nine  flasks  were 
taken  and  divided  into  sets  of  three.  The  same 
culture  solutions  were  placed  in  all  three  flasks — • 
i  gramme  of  Mannite,  0-2  gramme  of  Di-potassium 
phosphate  (K2HPO4),  0-02  gramme  Magnesium  sul- 
phate (MgSO4),  and  0*2  gramme  Calcium  carbonate 
(CaCO3).  The  first  three  flasks  had  nothing  in 
addition,  the  second  three  received  0-00017  gramme 
of  the  Phosphotungstic  acid  fraction — that  is,  the 
amount  obtained  from  i  gramme  of  treated  peat — 
and  the  third  set  received  a  corresponding  fraction 
of  the  Silver  nitrate  fraction,  the  amount  being 
0-000035  gramme.  Two  flasks  were  sterilized  to  act 
as  a  control.  At  the  end  of  ten  days  no  nitrogen 
had  been  fixed  in  the  sterilized  flasks,  3-9  milli- 
grammes had  been  fixed  by  the  first  series,  9-7  milli- 
grammes by  the  second,  and  10-4  milligrammes  by 
the  third. 

In  view  of  the  encouraging  results  obtained  in 
these  experiments  it  was  decided  to  'ascertain  more 
definitely  how  far  liquid  cultures  of  nitrifying 
organisms*  could  be  used  as  a  test  for  the  auximones. 
A  culture  was  originally  obtained  by  incubating 
garden  soil  in  Winogradsky's  medium.  Two  sub- 
cultures were  taken  from  this  initial  culture,  and 
eighteen  flasks  were  filled  with  pure  uninoculated 
culture  solution  (Winogradsky's).  These  were  all 
inoculated  with  material  from  the  second  sub- 
culture. The  first  series  received  nothing  in  ad- 
dition, each  flask  of  the  second  series  received 

*  These  are  organisms  which  have  the  property  of  converting 
Ammonium  salts  into  nitrates. 

8 


H4  THE  SPIRIT  OF  THE  SOIL 

the  Phosphotungstic  acid  fraction  derived  from 
i  gramme  of  the  treated  peat,  while  each  flask  of  the 
third  received  the  Silver  nitrate  fraction  from 
i  gramme  of  the  treated  peat.  Incubation  was 
carried  on  at  26°  C.,  and  at  the  end  of  forty-eight 
hours  no  scum  had  formed  on  the  flasks  which  had 
received  no  auximone,  but  nitrification  had  pro- 
ceeded at  a  normal  rate.  Both  sets  of  flasks  that 
had  received  auximones  showed  scum,  but  no 
nitrification.  Only  two  interpretations  of  these 
results  were  possible:  either  the  subculture  fur- 
nished a  satisfactory  test  for  auximones,  or  scum- 
forming  organisms  had  been  introduced  with  the 
auximones.  To  test  this  possibility  a  flask  contain- 
ing a  subculture  was  incubated  at  26°  C.  for  four 
days  with  no  result.  One  half  of  this  culture  was 
sterilized  by  heating  in  an  autoclave  for  half  an  hour 
at  160°  C.  To  this  and  to  the  unsterilized  half 
the  Phosphotungstic  acid  fraction  derived  from 
i  gramme  of  peat  was  added,  and  the  two  flasks 
were  incubated  for  three  days  at  26°  C.  The  un- 
sterilized flask  contained  a  thick  layer  of  scum, 
while  the  sterilized  flask  had  none.  The  explanation 
was  that  the  scum-forming  organism  is  present  in 
soil  cultures,  but  that  the  formation  of  the  scum  in 
this  medium  is  due  to  the  presence  of  the  auximone. 

This  experiment  was  several  times  repeated,  and 
the  scum  organism  was  found  in  each  of  several  soils 
tested.  Under  the  microscope  it  proved  to  consist  of  a 
mixture  of  beaded  rod  forms  and  spindle-shaped  forms 

Further  experiments  emphasized  the  amazing 
sensitiveness  of  this  bacterial  test  to  the  Silver 


ACCESSORY  FOOD  BODIES  115 

extract.  To  quote  one  of  the  experiments:  Six 
flasks,  A  to  F,  were  taken  and  filled  with  100  c.c. 
of  normal  culture  solution.  To  the  first  nothing 
was  added,  but  to  the  others  decreasing  amounts  of 
Silver  nitrate  extract.  The  quantities  used  and 
the  results  obtained  on  incubation  are  shown  in  the 
following  table : 


Parts  per  Million  of 

Silver  Nitrate  Ex- 

Result. 

tract  added. 

A.  100  c.c.  culture 

solution 

0 

None 

B.  Ditto     .  . 

4-0000 

Extremely  thick 

scum 

C.  Ditto     .. 

2-1000 

Thick  scum 

D.  Ditto     .  . 

0-3500 

Moderate  scum 

E.   Ditto     .  . 

0-0070 

Fair  scum 

F.  Ditto     .. 

0-0007 

No    appreciable   re- 

sult 

In  other  words,  when  the  Silver  nitrate  extract  was 
added  to  the  amazingly  small  extent  of  i  part  in 
15,000,000  an  appreciable  result  was  obtained. 

Tests  were  made  with  a  large  number  of  other 
organic  substances  to  see  whether  the  scum  would 
be  formed  in  their  presence.  The  result  in  every 
case  was  negative  until  100  parts  per  1,000,000  were 
added.  Even  then  the  characteristic  scum  was  not  ob- 
tained, as  the  whole  liquid  was  found  to  turn  cloudy. 

Further  comparative  tests  were  made  with  the 
accessory  food  bodies  that  had  been  found  to  give 
results  on  animals.  When  they  were  derived  from 
germinated  wheat,  dry  wheat,  peas,  or  yeast,  the 


n6  THE  SPIRIT  OF  THE  SOIL 

scum  organisms  made  their  appearance.  They  did 
not  appear  when  the  accessory  food  bodies  were 
derived  from  dry  maize  or  dry  peas.  It  seems  evi- 
dent that  these  scum-forming  organisms  are  able  to 
serve  as  a  satisfactory  test  both  for  auximones  and 
for  the  accessory  food  bodies  of  Hopkins. 

Tests  were  also  undertaken  with  fresh  and  rotted 
manures.  The  result  with  these  was  that  it  was 
found  that  the  quantity  of  auximones  present 
increased  with  the  progressive  decomposition  of  the 
organic  matter  of  manure.  The  amount  of  it  was 
relatively  small.  In  two-year-old  rotted  manure, 
compared  as  against  bacterized  peat,  a  better  scum 
was  obtained  with  the  fraction  from  ^  gramme  of 
peat  than  with  10  grammes  of  the  manure. 

A  source  from  which  the  auximones  can  readily 
be  derived  is  the  leguminous  plant.  Thus  the 
Phosphotungstic  acid  fraction  derived  from 
•jV  gramme  of  bean  nodules  gave  a  very  thin  film  of 
scum.  The  fraction  from  ¥\  gramme  of  bean  root 
gave  a  fair  growth,  while  with  TV  gramme  a  good 
growth  was  obtained.  When,  however,  beans  were 
grown  in  sterilized  sand  without  the  formation  of 
nodules  no  scum  at  all  appeared,  even  though  the 
extract  of  TV  gramme  of  root  was  used. 

As  regards  the  scum-forming  organisms  used  for 
the  test,  it  may  be  noted  that  they  require  no  organic 
Carbon,  but,  like  the  nitrifying  organisms  and  the 
sulphur  and  iron  bacteria,  they  are  able  to  assimilate 
Carbon  dioxide  by  chemo-synthesis.  They  are 
unable  to  live  on  nitrates,  but  must  derive  their 
Nitrogen  from  an  Ammonium  salt. 


ACCESSORY  FOOD  BODIES  117 

I  have  dealt  in  this  chapter  with  the  auximones 
at  greater  length  and  in  fuller  detail  than  some 
readers  may  think  that  the  subject  warrants. 

I  make  no  excuse  for  so  doing,  as  there  is  a  possi- 
bility that  in  the  auximones  derived  from  bacterized 
peat  we  may  have  a  substance  of  enormous  value. 
Wells,  in  his  book  of  brilliant  imagination,  The  Food 
of  the  Gods,  galvanized  the  public  into  an  appreciation 
of  the  meaning  of  vitamines.  In  treating  the  subject 
he  took  the  full  licence  of  the  novelist,  and  he  would 
doubtless  be  the  last  to  suggest  that  by  vitamines 
or  any  other  product  it  would  be  possible  to  upset 
the  unknown  factors  that  determine  the  limits  of 
the  growth  of  various  species.  Auximones  will 
never  threaten  the  world  with  the  menace  that  he 
so  graphically  painted,  but  it  is  a  fact  that  they  do 
aid  plants  to  attain  their  fullest  normal  growth,  and 
it  may  prove  to  be  a  fact  that  they  will  prove 
valuable  in  diseases  of  malnutrition.  A  preliminary 
experiment,  to  which  too  much  importance  must 
not  be  attached,  has  already  been  carried  out  at 
King's  College.  Some  chicks  were  taken  straight 
from  the  egg.  One  batch  of  them  were  fed  on  a 
physiologically  complete  diet,  and  all  naturally 
developed  poly  neuritis  gallinarum  and  died.  The 
other  batch  in  addition  to  this  diet  also  received 
Phosphotungstic  acid  extract.  They  died  also,  but 
later,  and  of  ordinary  chicken  diseases.  The  details 
of  the  experiment  have  not  been  published,  and  I  am 
mentioning  it  here  rather  in  the  hope  of  attracting 
physiologists  to  undertake  a  research  that  seems  as 
if  it  might  yield  valuable  results  than  as  stating  a 


n8  THE  SPIRIT  OF  THE  SOIL 

conclusion.  If  further  experiments  were  to  prove 
that  either  auximones  themselves,  or  auximones  sub- 
jected to  some  further  treatment,  were  able  to  act 
similarly  to  Hopkins's  accessory  food  bodies,  or  to 
Funk's  vit amines,  it  would  no  longer  be  necessary 
to  say  as  I  did,  quoting  Dr.  Watson- Wemyss  at  the 
outset  of  the  chapter:  "  The  difficulty  of  obtaining 
isolated  vitamines,  together  with  its  expense,  make 
its  general  use  at  present  impossible." 

The  subject  is  one  of  proved  general  interest,  as 
was  shown  by  the  public  notice  that  was  taken  of  the 
recent  agitation  on  the  subject  of  standard  bread. 
As  in  most  public  agitations,  there  were  occasions 
when  the  truth  was  lost  sight  of,  when  a  proved  fact 
was  applied  more  widely  than  was  scientifically 
justified,  but  the  fact  stood  behind  the  exaggerations 
that  at  times  threatened  to  conceal  it,  and  has 
become  part  of  the  stock  of  common  knowledge. 
Such  harm  as  resulted  was  trivial,  and  only  good 
can  come  of  the  general  recognition  of  the  fact  that 
without  vitamines  and  without  accessory  food  bodies 
it  is  impossible  for  either  plant  or  animal  to  be 
satisfactorily  nourished. 


CHAPTER  IX 

ELEMENTARY   CONCEPTIONS    OF   CHEMISTRY   IN 
RELATION  TO  THE  SOIL 

Difficulties  of  chemistry — The  elements  and  their  symbols — • 
Atoms — Mixtures  and  compounds — Molecules — The  formula 
and  the  equation — Affinities — Grouping  in  the  molecule — 
The  structural  formula — Acids,  neutrals,  and  bases — The 
COOH  group — Series  of  acids— Seventeen  possible  acids 
with  one  formula — Neutralization  of  acids — Oxidation — 
Reduction — Hydration — Dehydration — Ammonia — Carbo- 
hydrates, proteins,  fats,  and  amides. 

FEW  subjects  present  such  impenetrable  difficulties 
to  those  who  have  not  made  some  sort  of  a  set  study 
of  it  as  Chemistry.  Range  through  the  Arts  and 
Sciences  as  you  will,  and  the  subject-matter  of  them 
obtrudes  itself  on  your  everyday  life.  Zoology 
seems  simple  and  intelligible  to  those  who  have  not 
studied  it,  because  such  people  think  of  it  in  terms  of 
the  animals  with  which  they  are  familiar.  Our 
everyday  knowledge  of  plants  makes  all  of  us  some- 
what of  amateur  botanists.  The  man  who  can 
recognize  the  Great  Bear  and  a  half-dozen  of  the 
constellations  feels  confident  that  if  he  set  his  mind 
to  it  he  could  become  an  astronomer.  The  bicyclist 
imagines  himself  to  be,  and  to  some  extent  is,  an 
engineer.  Experience  of  roads  and  soils  makes  most 
men  in  a  way  geologists.  Electric  light  and  motor- 


120  THE  SPIRIT  OF  THE  SOIL 

ing  have  taught  men  something  of  electricity. 
When  the  untaught  man,  however,  finds  himself 
confronted  with  chemistry,  he  is  apt  to  feel  himself 
in  a  strange  world  with  no  means  of  determining  his 
bearings.  He  has  seldom  been  brought  face  to  face 
with  the  elements  of  which  chemistry  deals.  The 
air  he  breathes  is  not  only  a  mixture  of  Oxygen, 
Nitrogen,  water  vapour,  and  Carbon  dioxide,  but  he 
finds  that  it  is  a  storehouse  of  half  a  dozen  of  the 
so-called  rare  gases.  Iron,  the  metal  he  is  perhaps 
most  familiar  with,  he  learns,  has  Carbon  in  com- 
bination with  it,  and  by  the  addition  of  traces  of 
other  elements  may  change  its  properties  and 
develop  astounding  degrees  of  hardness.  The  gold, 
silver,  and  copper  coins  that  he  has  been  wont  to 
regard  as  pure  are  each  and  all  of  them  alloys.  Nor 
is  this  all.  The  first  book  that  he  opens  on  the 
subject  bristles  with  an  apparently  infinite  number 
of  mysterious  symbols.  Figures  are  scattered  about 
among  them,  some  on  the  line  and  some  beneath  it, 
and  if  he  chances  to  light  on  the  simplest  calcula- 
tion he  sees  it  at  once  stretching  to  four  places  of 
decimals. 

For  these  reasons  I  am  including  in  this  volume  a 
short  chapter  on  the  chemistry  of  the  soil  so  far  as 
we  are  concerned  with  it  in  connection  with  Nitrogen 
fixation,  in  the  hope  that  it  may  help  those  who  have 
no  knowledge  of  the  subject  to  get  a  clearer  appre- 
ciation of  the  problems  involved. 

Despite  the  complexity  of  nature  as  we  see  it 
around  us,  the  world  contains  only  a  few  elementary 
substances,  known  as  elements.  They  are  some 


SOME  CHEMICAL  CONCEPTS 


121 


eighty  in  number,  and  only  a  few  of  them  are  widely 
distributed.  About  a  score  of  them  are  concerned 
with  the  life  of  man  and  animals.  These  substances, 
however,  are  found  combined  in  all  sorts  of  different 
ways,  and  to  study  them  intelligently  it  is  necessary 
to  know  exactly  how  they  are  built  up.  Take,  for 
instance,  such  a  substance  as  starch.  A  single  grain 
or  molecule  of  starch  may  be  considered  without 
serious  error  from  our  standpoint  as  containing 
6  unit  grains  or  atoms  of  Carbon,  10  unit  grains  or 
atoms  of  Hydrogen,  and  5  unit  grains  or  atoms  of 
Oxygen.  If  2  unit  grains  or  atoms  of  Hydrogen, 
and  i  unit  grain  or  atom  of  Oxygen  are  added  to  it, 
the  starch  becomes  sugar.  All  this  clumsy  state- 
ment is  stated  in  the  language  of  the  chemist  in  the 
simple  equation : 

C6H1005+H20  =  C6H1206. 

The  mysterious  symbols  of  chemistry  are  in  most 
cases  the  first  letter  or  the  first  two  letters  of  the 
name  of  the  element.  Thus,  Carbon  is  written  C, 
and  Calcium,  to  differentiate  from  it,  Ca.  In 
some  instances  the  symbols  are  derived  from  the 
Latin  names.  Thus,  Iron  (Ferrum),  Fe,  etc.  The 
elements  with  which  we  are  concerned  in  agriculture 
(with  their  symbols)  are  the  following : 


Carbon 

C 

Sulphur 

S 

Hydrogen 

H 

Calcium 

Ca 

Oxygen 

O 

Magnesium 

Mg 

Nitrogen 

N 

Iron  .  . 

Fe 

Phosphorus 

P 

Potassium 

K 

Sodium 

Ma 

Copper 

Cu 

Chlorine 

Cl 

Aluminium 

Al 

Silicon 

Si 

Manganese 

Mn 

Lithium 

Li 

Zinc.  . 

Zn 

122  THE  SPIRIT  OF  THE  SOIL 

Experiment  has  proved  that  any  given  weight  of 
an  elementary  substance  consists  of  a  certain  number 
of  ultimate  particles  or  atoms  of  substance.  One 
may  conceive,  for  instance,  of  a  speck  of  Carbon 
enormously  magnified.  In  such  a  case  one  could — • 
to  assist  the  imagination — regard  it  as  consisting  of 
myriads  and  myriads  of  round  black  grains,  each  of 
them  the  exact  replica  of  the  others.  Each  of  these 
grains  would  be  an  atom  of  Carbon.  For  the  pur- 
poses of  general  chemistry  one  may  say  that  these 
atoms  are  indivisible. 

The  enormous  majority  of  substances,  all,  in  fact, 
except  the  elements  themselves,  are  either  mixtures 
or  compounds.  In  a  mixture  the  atoms  would  lie 
more  or  less  any  way  like  a  series  of  differently 
coloured  marbles  jumbled  together  in  a  bag.  In  a 
compound  there  would  be  no  single  atoms  at  all,  but 
groups  of  atoms,  two,  three,  four,  or  even  hundreds 
and  thousands  firmly  held  together,  each  group  being 
the  exact  counterpart  of  each  other  group.  In  most 
instances,  too,  the  atoms  of  an  element  by  itself 
form  little  groupings  or  molecules.  Thus,  the  gas 
Oxygen  does  not  exist  in  the  air  as  single,  but  as 
twin  atoms.  As  will  be  seen,  the  chemist,  therefore, 
writes  it  as  O2,  and  not  0^ 

In  connection  with  chemical  work  figures  are  used 
in  two  ways.  Take  such  a  substance  as  Sulphuric 
Acid.  This  might  be  written  H2S!O4  (it  is  written 
H2SO4),  and  means  that  the  unit  or  molecule  of 
Sulphuric  Acid  has,  combined  together,  2  units  or 
atoms  of  Hydrogen,  i  unit  or  atom  of  Sulphur,  and 
4  units  or  atoms  of  Oxygen.  In  other  words,  the 


SOME  CHEMICAL  CONCEPTS  123 

little  figures  placed  below  and  immediately  after  the 
chemical  symbol  state  the  number  of  atoms  con- 
tained in  the  molecule.  Where  no  figure  is  given  it 
is  understood  that  only  a  single  atom  is  present. 
When  an  expression  has  a  figure  on  the  line  before 
it,  such  as  2H2SO4,  or  3H2SO4,  it  means  that  two  or 
three  molecules  of  Sulphuric  acid  are  concerned.  It 
is  also  possible  to  bracket  subgroups  in  a  compound, 
and  place  a  small  figure  below  the  line  following 
the  bracket.  In  such  a  case  there  is  that  number 
of  the  group  in  the  compound.  Thus,  when  the 
chemist  writes — 

6NaCN+Fe(OH)2=Na4Fe(CN)6+2NaOH, 

he  means,  if  six  molecules  of  Sodium  Cyanide  (com- 
posed each  of  one  atom  of  Sodium,  one  of  Carbon, 
and  one  of  Nitrogen)  are  mixed  with  one  molecule 
of  Ferrous  Hydroxide  (composed  of  one  atom  of 
Iron  combined  with  two  groups,  each  consisting  of 
one  atom  of  Oxygen  and  one  atom  of  Hydrogen, 
reaction  occurs,  and  we  get  [that  is  the  chemical 
meaning  of  the  symbol  =  ]  one  molecule  of  Sodium 
Ferrocyanide  (consisting  of  four  atoms  of  Sodium 
combined  with  one  atom  of  Iron,  and  six  groups,  con- 
sisting each  of  an  atom  of  Carbon  and  an  atom  of 
Nitrogen),  and  two  molecules  of  Caustic  Soda  (con- 
sisting of  one  atom  of  Sodium  combined  with  one 
atom  of  Oxygen  and  one  atom  of  Hydrogen) . 

The  question  naturally  suggests  itself  how  these 
various  compounds  are  held  together.  Various 
workers  have  suggested  explanations  of  the  problem, 
but  we  are  concerned  here  with  what  happens  rather 


124  THE  SPIRIT  OF  THE  SOIL 

than  with  why  it  happens.  Experiment  has  shown 
that  the  different  atoms  have  varying  affinities. 
We  may  regard  these  affinities  as  hooks  sticking  out 
from  the  smooth  surface  of  the  atom,  one  hook  corre- 
sponding to  one  affinity.  Of  the  commoner  elements 
in  agricultural  chemistry,  we  can  state  that  carbon 

r   r 

has  four  affinities     *—  C  -*  usually  written  more  simply 

i  -i 

—  C  —     ;  Hydrogen  one,  H  —  ;  Oxygen  two,  —  O  —  ; 

I     J 
Nitrogen  sometimes  three  and  sometimes  five,  —  N  — 

I  I 

or  —  N  —  ;   Phosphorus  five,   —  P  —  ;   Sulphur  six, 

ix 

or  two,  —  S  —  or  —  S  —  •;  Sodium  one,  Na  —  ;   and 

I  \ 
Potassium  one,  K  —  . 

The  statement  can  be  made  generally  that  there 
cannot  exist  any  compound  in  which  any  hooks  are 
left  free,  or,  in  chemical  terms,  all  affinities  must  be 
satisfied.  Thus,  while  the  substance  water  exists, 

O  TT\ 

Tj_!T~    ~Z_jr,  usually  written  S/O,  the  substance 

OH  cannot  exist  because  it  would  leave  an  affinity 
unsatisfied,  thus  : 


In  organic  chemistry  especially  it  is  of  vital 
importance  to  know  how  the  atoms  are  arranged  in 
the  molecule,  because  the  different  groups  give  very 
different  results,  and  two  substances  may  contain 
exactly  the  same  atoms  with  the  same  number  of 


SOME  CHEMICAL  CONCEPTS 


125 


each,  but  the  resulting  properties  be  quite  different. 
Thus,  Methyl  Cyanide— 


CH3CN  or 


I 


H 

H— C— CEEN 
H 


is  a  colourless  liquid,  possessing  a  strong  but  not 
disagreeable  smell,  and  is  readily  soluble  in  water. 
Methyl  Isocyanide,  however — 


CHUNG  or 


H 


H 


-N=C 


is  also  a  colourless  liquid,  possessing,  as  Perkin  and 
Kipping  state  without  exaggeration,  an  almost 
unbearable  odour  and  poisonous  properties. 

It  is  extremely  important,  and  also  rather  difficult, 
to  get  a  clear  appreciation  of  what  is  meant  by 
the  terms  acid,  neutral,  and  base,  but  a  rough  defi- 
nition is  easy  enough.  An  acid  is  a  substance  that 
reddens  blue  litmus-paper  and  that  has  a  sour  taste, 
a  neutral  substance  has  no  effect  on  litmus-paper,  a 
basic  substance  turns  red  litmus-paper  blue,  and 
the  more  common  bases,  such  as  Caustic  Potash, 
Caustic  Soda,  etc.,  have  an  astringent  caustic  taste. 
It  is  generally  true  that  an  acid  body  has  a  Hydrogen 
that  can  easily  be  replaced  by  a  metal.  Thus — 


HCl         +          NaOH 

Hydrochloric  Acid.        Caustic  Soda. 

Acid.                     Base. 
CH3COOH      +      NaOH 

Acetic  Acid.                Caustic  Soda. 

Acid.                    Base. 

=       NaCl          +         H20 

Sodium  Chloride.                   Water. 

Neutral.               Neutral. 
=        CH3COONa     +     H2O 

Sodium  Acetate.               Water. 

Neutral.            Neutral. 

126  THE  SPIRIT  OF  THE  SOIL 

It  is  also  generally  true  that  bases  are  formed  by 
metals  combined  with  the  group  OH  —  e.g.,  NaOH, 
etc.  —  and  that  acids  are  formed  when  non-metals 
are  combined  with  the  group  OH  —  e.g.,  H2SO4 
(Sulphuric  Acid). 

H~°x° 

H—  (X     ^O 

But  there  are  many  exceptions,  some  more  ap- 
parent than  real,  such  as  HC1  (Hydrochloric  Acid) 
and  all  the  organic  acids,  such  as  CH3COOH  (Acetic 
Acid),  where  the  CH3  group  may  be  regarded  as 
acting  as  if  it  were  a  non-metal  element. 

There  are  not  many  groups  that  we  have  to 
consider  for  the  present  purpose  of  this  book.  The 
group  of  chief  importance  is  the  COOH  group. 
This  is  the  standard  grouping  that  gives  acid  proper- 
ties to  organic  bodies,  and  that  can  be  neutralized 
when  the  hydrogen  in  it  is  replaced  by  such  a  sub- 
stance as  the  Calcium  of  Lime.  The  atoms  are 

combined  as  follows  :  —  C\  QTJ>  and  it  will  be  noticed 

that  the  Carbon  has  one  affinity  unsatisfied.  If  a 
Methyl  group  (CH3)  is  linked  on  to  this  we  have 
Acetic  Acid,  one  of  the  simplest  of  all  organic  bodies  : 

H 

I      j& 

H—  C—  C 


From  this  a  whole  series  of  organic  acids  can  be 
formed  by  the  simple  system  of  inserting  any  desired 
number  of  the  group  CH2. 


SOME  CHEMICAL  CONCEPTS  127 

Thus— 

H    H 

i      I       ^0 
H— C— G— Cf 

I     !      NDH  I     |     |      XOH 

H    H 

Propionic  Acid.  Butyric  Acid. 

and  so  forth. 

This  does  not  end  the  degree  of  complexity  of  the 
formation  of  organic  compounds.  The  formula  for 
Butyric  Acid,  for  instance,  adding  up  the  Carbons, 
Hydrogens,  and  Oxygens,  is  C4H8O2,  but  the  formula 
can  also  be  written — 


in  which  case  you  get  a  substance  with  different 
properties,  known  as  Isobutyric  acid.  When  three 
more  CH2  groups  are  added,  you  ggt  a  body  called 
Heptylic  Acid. 

It  is  possible  to  write  no  fewer  than  seventeen 
different  structural  formulae  for  Heptylic  Acids  satis- 
fying the  necessary  conditions,  though  the  formula 
is  a  simple  one  (C7H14O2),  and  of  these  seventeen 
hypothetically  possible  bodies  nine  are  actually 
known.  The  number  of  hypothetically  possible 
acids  from  stearic  acid,  which  is  far  from  being  the 
most  complex  of  the  series  known  (C18H36O2),  can  be 
imagined. 


128  THE  SPIRIT  OF  THE  SOIL 

The  complexities  of  these  substances  do  not  con- 
cern us.  What  has  clearly  to  be  borne  in  mind  as 
regards  them  is  the  simple  means  by  which  their 
acid  properties  can  be  neutralized.  This  can  be  done 
readily  by  means  of  Lime  [Ca(OH)2]  or  Ammonia 
(NH4OH,  orNH3).  Thus— 

H  H 

C-C^  H—  C—  C/ 

|          X)H  XO 

H  OH  H  \          nH\ 

0 


+  Ca<;  =  Ca  + 

H  Npfl  H  /          "H/ 

I         /OH  |          /> 

H—  C—  C/  H—  C—  C< 

i    ^°  i    %0 

Acetic  Acid.  Lime.  Calcium  Acetate.  Water. 

or  — 

H  H 

I         J°         S\  I         ^°          /H     H\ 

H—  C—  C<;        +H^N_0_H=H_(>_C^  /H+      \Q 

I      XOH   j*/  i      xo—  N:S:  H/ 

H  H 

rl 

Acetic  Acid.  Ammonia.  Ammonium  Acetate.  Water. 

Four  fundamental  processes  occur  in  the  soil  in 
connection  with  the  decomposition  of  organic  matter. 
Oxygen  is  added  to  or  taken  from  the  molecule,  and 
the  elements  of  water  are  added  to  or  taken  from 
the  molecule.  If  some  indication  can  be  given  to 
the  reader  as  to  how  these  processes  can  occur,  the 
general  scheme  of  soil  chemistry  will  easily  be 
grasped. 

In  the  changes  that  carbohydrates  undergo  in 
becoming  peat  the  most  striking  feature  is  the  way 
in  which  the  molecule  is  continually  increasing  the 


SOME  CHEMICAL  CONCEPTS 


129 


percentage  of  Carbon  that  they  contain.  One  way 
in  which  this  is  effected  is  by  the  loss  of  water.  The 
exact  changes  which  occur  are  not  known,  but  the 
following  formulae  show  how  such  a  change  might 
be  effected.  The  first  formula  shows  how  two 
molecules  of  Glucose,  2C6H12O6,  might  be  concen- 
trated by  loss  of  water,  and  form  a  molecule  richer 
in  Carbon,  C12H14O7  ;  the  second  how  this,  with  one 
other  molecule  of  Glucose,  could  change  to  the  third, 
showing  a  still  greater  amount  of  Carbon.  Thus  — 


I     ;;;.:;;:;  ....................  :     I 

H—  C—  O—  H  H—  C—  O—  H 


130  THE  SPIRIT  OF  THE  SOIL 


A  reaction  very  commonly  met  with  is  the  change 
of  substances  through  the  addition  of  the  elements 
of  water.  This  is  often  effected  by  boiling  the  sub- 
stance with  dilute  acid.  Thus,  the  sugar  Lactose, 
if  boiled  with  dilute  Hydrochloric  acid,  yields  the 
sugars  Glucose  and  Galactose,  a  molecule  of  water 
being  added  in  the  process  according  to  the 
formula : 

C12H22On     +     H20     =     C6H1206     +     C6H1206 

Lactose.  Water.  Glucose.*  Galactose.* 

At  first  sight  it  seems  curious  that  the  effect  of 
boiling  with  such  a  substance  as  a  dilute  acid  should 
be  to  add  the  elements  of  water.  It  has  to  be 
remembered  that  when  such  a  body  as  Hydrochloric 
Acid  is  in  solution  it  splits  up.  The  molecules  of  the 
acid  no  longer  move  in  the  liquid  as  the  unit  HC1, 
but  in  a  peculiarly  active  form  as  H —  and  Cl — ,  con- 

*  These  two  substances,  though  they  have  the  same  composi- 
tion, and  in  a  sense  the  same  structural  formulae,  have  their 
atoms  differently  arranged,  so  that  one  would  be  the  looking- 
glass  picture  of  the  other. 


SOME  CHEMICAL  CONCEPTS  131 

tinually  combining  and  breaking  apart.  The  water 
also  will  be  going  about  in  the  form  of  H —  and  — OH. 
Then  in  the  solution  we  may  get  some  such  com- 
bination as — 

H— Cl >    H—  and  Cl— 

H2O >    H—  and  — O— H 

These  might  recombine  on  the  lines — 
H—    jci— "  H— I    — o— H 

The  elements  of  water  may  split  away  through 
the  formation  of  Hydrochloric  acid,  as  shown  by  the 
dotted  ring,  and  it  is  a  commonly  known  chemical 
fact  that  compounds  in  the  act  of  formation  or 
decomposition  will  have  more  active  chemical 
properties  than  when  they  are  in  a  stable  state.  It 
is  perhaps  for  some  such  reason  as  this  that  a  common 
means  for  adding  the  elements  of  water  to  a  com- 
pound is  to  boil  with  dilute  acids. 

The  addition  of  Oxygen  to  an  organic  compound 
may  readily  result  in  an  acid  being  formed.  Thus,  if 

Oxygen  were  added  to  any  of  the  bottom  C — H 

O 

groups  in  the  structural  formula  given  above,  an 
atom  of  Oxygen  would  pass  in  between  the  Carbon 
and  the  Hydrogen  to  form  the  typically  acid  group 

I 
C — 0 — H.     On  the   other  hand,    the   addition   of 

II 
O 

Oxygen  may  destroy  the  acid  properties  by  eliminat- 


132  THE  SPIRIT  OF  THE  SOIL 

ing  the  Carbon  altogether  from  the  molecule,  the 
group  splitting,  leaving  the  — O — H  to  link  on  to 

another  carbon,  and  forming  Q^C    (CO2).      Thus 

Formic  acid  arid  Oxygen  will  yield  C02  and  water  : 

/£>  O 

H — C\  # 

NDH+O=C    +  H— OH 

Formic  Acid.  ^^ 

O 

By  adding  Hydrogen  to  an  organic  compound  its 
constitution  may  be  profoundly  modified.     Thus,  the 

C — H   group   referred  to   above   may,   under    the 

II 

O 

influence  of  nascent  Hydrogen,  be  changed  into  an 
alcohol,  thus : 

O-H+aH    — >    H— C— H 

O  O— Hj 

or,  to  give  an  actual  equation : 
H 


U 

Ethyl  Alcohol. 

Another  reaction  of  considerable  importance  in 
connection  with  organic  decomposition  is  concerned 
with  Ammonia.  The  Nitrogen  contained  in  protein 
molecules  is  frequently  given  off  during  decompo- 
sition in  the  form  of  Ammonia,  and  acids  present  in 


SOME  CHEMICAL  CONCEPTS  133 

the  soil  are  in  this  way  neutralized.     Thus  one  would 
get  the  equation : 

H  H  H 

/£)         TT\  /&  IT      H\ 

Hr*      f^js  .    n\-».T      /-\      TT       TT /-* fij^  t  *•*•  i-        No 

— U — L/v  ~r  TT  /-tN — \J — ri  =  n — \~> — v>\ 


I      XOH    £7  I         -    _ 

H  H  VH 

Acetic  Acid.  Ammonia.  Ammonium  Acetate.  Water. 

Base.  Neutral, 

In  conclusion,  a  few  definitions  may  prove  useful : 

A  CARBOHYDRATE  is  a  compound  of  Carbon, 
Hydrogen,  and  Oxygen,  the  two  latter  elements 
being  present  in  the  same  proportions  as  they  are 
present  in  water.  To  this  class  belong  the  various 
celluloses,  starches,  and  sugars. 

PROTEINS. — These  all  contain  Carbon,  Hydrogen, 
Oxygen,  and  Nitrogen.  Phosphorus,  Sulphur,  and 
a  few  other  elements  are  also  often  present.  It  is  a 
characteristic  of  the  class  that  the  molecule  is  large, 
and  contains  a  number  of  complex  groupings. 

FATS. — These  are  neutral  bodies  consisting  of  a 
combination  of  Glycerine  and  the  so-called  Fatty 
Acids — i.e.,  acids  of  the  Formic  and  Acetic  Acid 
group,  which  has  CnH2nO2  as  the  common  formula 
of  the  group,  n  being  any  whole  number. 

AMIDES. — These  enter  largely  into  decomposition 
and  other  changes.  They  may  be  regarded  as 
derivatives  of  Ammonia  (NH3).  They  are  written 
/H, 

place  of  simply  attached  Hydrogen  in  organic  com- 
pounds.    Their    importance    in    Nature    may    be 


134  THE  SPIRIT  OF  THE  SOIL 

appreciated  by  the  statements  that  the  formula  for 
Urea  is — 

/H 


o=c; 


\H 

and  that  the  amide  is  an  important  constituent  of  the 
various  alkaloids. 

In  reading  this  chapter  the  caution  must  be  made 
against  too  literal  an  interpretation  of  many  of  the 
above  statements.  No  one,  for  instance,  imagines 
that  an  atom  is  a  rounded  body  with  a  number  of 
hooks  on  it.  Recent  research,  in  fact,  would  suggest 
rather  that  it  would  be  found  to  be  comparable  with 
a  firmament.  To  derive  any  value  from  these  more 
modern  conceptions,  however,  a  chemical  training 
is  necessary,  and  I  have  thought  it  better  to  describe 
the  cruder  views  that  very  largely  obtained  in  the 
recent  past,  as  they  are  rigidly  true  in  so  far  as  they 
gave  and  still  give  a  true  expression  to  the  majority 
of  the  facts  with  which  the  working  chemist  is  called 
upon  to  deal. 


CHAPTER  X 

THE  TESTING  OF  HUMOGEN 

Difficulties  in  sciences  dealing  with  living  organisms — Complexity 
of  biological  problems — Masking  of  cause  and  effect — Nitro- 
bacterine — Adoption  of  the  method  by  America — Essential 
to  supply  bacteria  with  food — Nature's  methods  with  the 
embryo — Comparison  with  bacterized  peat — Richness  of 
the  peat  in  humus — Response  of  the  laboratory  plants — 
Experiments  at  Kew — General  results  of  three  years'  work — 
Plant  fertilizers  used — Details  of  improvement  noted — 
Experiments  at  Tuckswood  Farm  :  Tomatoes.  Beans. 
Potatoes — A  curious  failure — Need  for  early  use  of  humogen 
— Mr.  Weathers's  experiments:  Marguerites.  Pyrethrums. 
Forget-me-nots.  Rhubarb.  Cabbages  —  Digging  in  of 
humogen. 

THERE  is  one  inherent  difficulty  attaching  inevitably 
to  all  sciences  that  have  to  deal  with  living  organ- 
isms— the  looseness  of  the  causal  relations.  Hence 
many  of  the  volumes  on  philosophy.  Hence  the 
fierceness  of  the  fighting  between  those  who  insisted 
on  the  doctrine  of  predestination  and  those  who 
championed  the  doctrine  of  free  will.  Hence,  too, 
the  keen  controversy  that  is  waged  even  to-day  on 
such  matters  as  vitalism  in  physiology;  or,  to  go 
from  large  issues  to  small,  the  campaign  of  the  anti- 
vivisectionists.  Perhaps  the  latter  question  illus- 
trates the  argument  best.  Many  people  who  know 
that  the  injection  of  morphia  into  a  cat  violently 

135 


136  THE  SPIRIT  OF  THE  SOIL 

excites  it,  whereas  the  injection  of  it  into  a  man  and 
into  most  other  animals  serves  to  soothe  the  nerves 
and  induce  sleep,  will  have  it  that  the  experimental 
physiologist  is  following  a  will-o'-the-wisp  when  he 
attempts  to  draw  general  conclusions  from  the 
experiments  he  performs  on  the  lower  animals.  I 
have  frequently  been  told  that  experiments  con- 
ducted on  the  dog,  such  as  problems  of  digestion, 
are  valueless  because  the  dog  will  swallow  and  digest 
bones,  whereas  the  normal  man  who  ate  his  meals 
on  similar  lines  would  suffer  terribly  from  indigestion. 
The  main  underlying  fallacy  vitiating  the  anti- 
vivisection  campaign — when  the  opposition  is  not 
due  merely  to  sentimentalism — is  the  common  belief 
that  in  cases  where  living  tissue  is  concerned  the 
relation  between  cause  and  effect  is  less  rigid  than 
it  is  in  the  case  of  lifeless  matter.  Scientific  biology 
is  frankly  based  on  the  principle  that  causal  rela- 
tions do  obtain  rigidly  so  far  as  the  material  side  of 
life  is  concerned,  and  many  biologists — returning  to 
the  problem  of  predestination  and  free  will — would 
hold  something  closely  akin  to  the  doctrine  of  pre- 
destination, and  contend  that  every  act  is  the 
inevitable  result  of  an  intensely  complex  set  of 
causes. 

In  tracing  out  causal  relations  in  biology  the 
worker  is  confronted  with  formidable  difficulties. 
While  the  physicist  or  chemist  is  usually  able  to 
simplify  his  problem  by  eliminating  all  confusing 
issues,  the  biologist  has  present,  as  the  basis  of 
nearly  all  his  work,  the  intensely  complex  animal  or 
vegetable  cell,  or  the  even  more  complex  living 


THE  TESTING  OF  HUMOGEN  137 

organism.  No  one  cell  is  exactly  the  same  as  any 
other  cell,  but  the  cell  of  any  given  tissue  possesses 
certain  properties  varying  within  limits  round  a 
common  mean.  Some  chemists  believe  that  a 
similar  doctrine  holds  about  the  elements — for 
instance,  that  one  atom  of  Nitrogen  is  not  the  same 
as  another  atom  of  Nitrogen,  but  that  the  atoms 
themselves  have  certain  limits  within  which  they, 
too,  are  able  to  vary. 

The  complexity  of  the  living  cell,  and  the  conse- 
quence of  this  complexity — that  cause  and  effect  are 
frequently  masked — has  created  considerable  diffi- 
culties in  the  researches  connected  with  bacterized 
peat.  The  problem  of  Nitrogen  fixation  by  means 
of  bacteria  in  the  case  of  leguminous  plants  had  been 
satisfactorily  worked  out  in  the  laboratory  some 
years  ago,  and  in  his  nitrobacterine  Professor 
Bottomley  had  obtained  a  form  of  culture  which 
gave  satisfactory  results.  Tested  a  little  prema- 
turely, perhaps,  under  glass  and  field  conditions,  the 
nitrobacterine  gave  several  failures  because  various 
factors  that  were  eliminated  successfully  in  the 
laboratory  upset  the  necessary  conditions  when  the 
bacteria  were  set  to  work  on  the  land.  Scientifically, 
nitrobacterine  was  a  success.  As  has  been  stated 
previously,  the  American  Board  of  Agriculture 
during  the  last  few  years  has  studied  these  field  diffi- 
culties, and  is  now  using  a  preparation  similar  to  the 
nitrobacterine  that  in  this  country  was  too  hastily 
condemned  by  many  who  failed  to  get  results. 

One  of  the  essential  difficulties  in  connection  with 
the  old  material  was  to  insure  that  the  bacteria, 


138  THE  SPIRIT  OF  THE  SOIL 

when  placed  in  the  ground,  should  have  a  suitable 
medium  in  which  to  work.  The  principle  is  one 
universally  recognized  in  Nature.  The  young  em- 
bryo in  the  seed  is  sent  out  by  the  parent  plant  with 
a  stock  of  food  material  that  makes  it  independent 
for  several  days  of  the  soil  on  which  it  falls.  In  the 
egg  the  embryo  starts  its  life  with  a  store  of  material 
ready  for  its  needs  several  thousand  times  greater 
than  itself.  In  the  mammal  the  young  embryo 
develops  firmly  fixed  to  its  parent,  and  even  after 
birth,  by  the  strength  of  the  maternal  instinct, 
Nature  insures  that  it  shall  have  for  months  to  come 
an  abundant  supply  of  the  food  that  it  requires. 

Nitrobacterine  was  a  compromise  between  the 
earlier  system  of  the  Germans  and  Americans  and 
that  used  with  bacterized  peat.  In  the  cotton-wool 
preparations  the  bacteria  were  sent  out  with  no 
food-supply  to  nourish  them,  and  many  of  them  died 
before  ever  they  reached  the  land  they  were  intended 
to  fertilize.  Nitrobacterine  (earth  impregnated  with 
bacteria)  through  the  humus  it  contained,  insured 
that  the  bacteria  should  have  some  food  to  support 
their  life  during  the  period  of  waiting ;  but  the  system 
of  utilizing  them  carried  with  it  the  objection  that 
on  being  applied  to  the  soil  they  had  at  once  to 
secure  their  food  from  the  ground  in  which  they 
found  themselves.  The  failures  with  the  prepara- 
tion showed  that  an  important  factor  had  been 
neglected,  and,  unconsciously  to  some  extent,  the 
laboratory  workers  were  thrown  back  to  imitate  the 
system  followed  by  Nature  in  the  egg  and  seed. 
Peat  was  a  substance  rich  in  the  raw  material  of 


THE  TESTING  OF  HUMOGEN  139 

humus.  It  was  known  that  in  time,  under  the 
influence  of  bacteria,  the  peat  changed,  forming 
soluble  humus,  and  experiments  were  made  to  see 
whether  the  process  could  not  be  hastened  by  arti- 
ficial means  so  that  the  bacteria  might  be  distributed 
in  the  soil  with  an  abundant  supply  of  food  to 
enable  them  to  start  their  growth. 

The  success  of  treating  the  peat  with  bacteria  was 
startling  in  the  unexpectedness  of  its  results.  On 
testing  peat  that  had  been  exposed  to  bacterial 
action  it  was  found  to  be  amazingly  rich  in  soluble 
humus,  to  yield,  in  fact,  fifty  to  eighty  times  as  much 
as  could  be  obtained  from  a  corresponding  weight  of 
the  best  rotted  stable  manure.  Laboratory  experi- 
ments followed.  As  was  to  be  expected,  the  Nitrogen- 
fixing  bacteria,  Bacillus  radicicola  and  Azotobacter 
chroococcum  flourished  and  multiplied  when  placed 
in  such  a  medium.  Plants,  too,  responded  readily 
to  the  peat.  When  grown  in  sterilized  sand  watered 
with  the  peat  extract  they  grew  luxuriantly,  develop- 
ing healthy  roots,  giving  luxuriant  foliage,  and 
coming  more  rapidly  to  maturity,  thus  proving  that 
Humogen  contained  everything  necessary  for  plant 
growth. 

The  exact  position  of  the  work  at  this  stage  was 
defined  by  Professor  Bottomley  in  a  paper  he  read 
before  the  British  Association  at  Dundee  in  1912. 
His  official  summary  of  the  paper  giving  the  essential 
facts  was  as  follows : 

"  Peat-moss  litter  is  said  to  be  '  entirely  unsuited 
for  the  growth  of  plants.'  It  is  acid  in  reaction,  and 
contains  no  soluble  humates. 


140  THE  SPIRIT  OF  THE  SOIL 

"  It  has  been  found,  however,  that  when  peat  is 
treated  with  certain  micro-organisms  a  large  quantity 
of  soluble  humate  is  obtained,  and  the  peat  is  ren- 
dered alkaline.  An  aqueous  extract  of  this  treated 
peat  (i  part  peat  to  200  parts  water)  will  supply  all 
the  plant-food  necessary  for  successful  water-culture 
experiments.  As  no  trace  of  nitrate  was  found  in 
the  culture  solutions  during  the  whole  course  of  the 
experiments,  it  is  evident  that  the  nitrogen  need  of 
the  plants  was  supplied  by  some  form  of  organic 
nitrogen  present  in  the  solution. 

"  Water-cultures  with  tomato  seedlings,  ger- 
minated in  sterilized  sand,  showed  that  the  plants 
failed  to  grow  in  raw  peat  extract,  but  in  treated 
peat  extract  the  plants  grew  well,  flowered,  and 
produced  fruit.  Experiments  with  buckwheat, 
radish,  and  barley  gave  similar  results." 

In  view  of  the  disappointment  with  nitrobacterine 
it  seemed  unwise  to  attempt  to  generalize  from  the 
laboratory  results,  and  three  years  ago  the  authori- 
ties at  Kew  Gardens  were  asked  if  they  would  be 
willing  to  conduct  experiments  with  the  new 
material. 

The  authorities  at  Kew  consented.  It  is  un- 
necessary to  state  that  Kew  Gardens  are  ideal  for 
such  a  purpose,  having  the  facilities  necessary  for 
conducting  large  scale  experiments,  and  the  per- 
sonnel competent  to  experiment  on  rigidly  scientific 
lines.  There  was  an  additional  advantage,  however, 
about  Kew.  Experiments  had  already  been  tried 
there  with  nitrobacterine,  and  had  given  negative 
results.  Naturally,  therefore,  the  authorities  were 
inclined  to  be  sceptical,  and  the  stringency  of  the 
tests  to  be  made  was  insured. 


THE  TESTING  OF  HUMOGEN  141 

In  the  first  year  the  effect  of  using  the  peat  in 
various  quantities  on  plants  grown  in  ordinary  soil 
was  tested,  and  plants  were  grown  in  ordinary  soil 
and  other  media  as  a  control.  Commenting  early  in 
1914  on  the  results  obtained,  Mr.  J.  Coutts,  of  Kew 
Gardens,  said  (Journal  of  the  Royal  Society  of  Arts, 
March  15,  1914)  that  "  the  plants,  beyond  ordinary 
details,  had  no  special  attention  during  growth  other 
than  that  devoted  to  starting  them ;  after  a  fortnight 
or  so  they  were  left  to  themselves.  The  results  in 
some  cases  were  extraordinary,  and  not  comparable 
with  those  obtained  from  ordinary  nitrogenous 
manure.  Experiments  had  been  made  to  determine 
whether  peat  afforded  plants  a  greater  power  of 
resisting  the  eel-worm,  and  in  this  connection  the 
carnations  showed  the  most  striking  results.  In  the 
case  of  the  peat -treated  plants  there  was  little  trace 
of  eel-worm  after  two  months'  growth,  whereas  the 
nitrated  plants  were  badly  affected  within  a  fort- 
night. Another  experiment  was  made  with  chrys- 
anthemum plants  in  the  open,  planted  at  the  same 
time  and  under  the  same  conditions.  One  section 
of  this  planting  was  treated  with  2  ounces  of  peat 
to  the  square  yard,  a  second  with  4  ounces,  while 
a  third  section  was  treated  with  dried  sewage 
sludge,  and  a  fourth  with  nitrates.  The  differences 
in  results  were  marked.  The  section  treated  with 
the  smaller  quantity  of  peat  seemed  as  good  as  that 
which  had  received  a  larger  allowance.  Again  the 
sludge  section  was  considerably  superior  to  that 
which  was  nitrated,  although  much  inferior  to  the 
peat-treated  sections,  the  action  being  slower.  It 


142 


THE  SPIRIT  OF  THE  SOIL 


was  evident  that  there  was  something  in  the  nature 
of  manurial  effects  in  the  peat,  the  root  development 
of  the  plants  being  very  marked." 

The  experiments  conducted  during  the  first  year 
at  Kew — other  experiments,  as  is  shown  in  Ap- 
pendix B,  were  in  progress  elsewhere — were  very 
striking,  and  when  in  the  second  year  they  were  con- 
siderably extended,  the  beneficial  results  obtained 
from  the  bacterized  peat  were  fully  confirmed. 
During  the  present  year  I  visited  the  gardens  to 
see  the  progress  of  the  experiments  now  in  progress. 
The  final  results  of  this  year's  work  have,  of  course, 
not  yet  been  obtained,  but  the  influence  of  the  peat 
on  the  plants  at  present  growing  there  is  extremely 
striking.  For  the  various  classes  of  work  there  nine 
different  soil  mixtures  have  been  used  for  compara- 
tive purposes.  They  are  as  follows: 


Soil 

Leaf  mould 

Sand 

As  No.  i,  but  sterilized 


3.  Sterilized  soil  54-6 
Leaf  mould  18-6 
Sand         . .  8  to  9 
Lime  rubble  8  to  9 
Sewage  sludge  8  to  9 
Basic  slag  0-5 
Bone  meal  0*5 
Soot         ...                                                        0-5 
Sulphate  of  potash                                         0*3 

4.  Sterilized  soil                                ^  80 
Humogen                                      "*  10 
Sand        . .  10 

5.  As  No.  2,  but  newly  sterilized  soil. 

6.  No.  2,  plus  0-04  per  cent.  Gafsa  Phosphate. 

7.  No.  6,  plus  12-5  per  cent.  Humogen. 

8.  No.  2,  plus  0-43  per  cent.  Gafsa  Phosphate. 

9.  No.  8,  plus  I2'5  per  cent.  Humogen. 


soil. 


Per  Cent. 
66 

22 
12 


.^^^   O 
a)       en 


"Jiff 

(XH       ^Q  ~     &>  "^ 
0)    U    tfl    O 


.   s  > 

" 


'   ^ 
1  1  T-E 

1,5         <U 

Q  rt1^  S 
Q  <u  o  g 

c£  ?>> 
—  H  6  w 


THE  TESTING  OF  HUMOGEN  143 

A  great  variety  of  plants  have  been  used  for 
experiments,  Cotton,  Tobacco,  and  Fuchsia  being 
among  the  numbers.  In  most  instances  the  plants 
grown  in  mixture  No.  4  are  so  markedly  superior  to 
those  for  which  any  other  mixtures  have  been  used 
that  the  difference  is  apparent  to  the  casual  glance  in 
the  increased  size  and  improved  healthiness  of  the 
treated  plants.  Occasionally  the  complete  fertilizer 
mixture,  a  mixture  containing  every  possible  form  of 
food  that  a  plant  can  require,  has  given  as  good 
results,  but  this  is  exceptional.  What  is  especially 
noticeable  at  Kew  Gardens  is  the  increased  root 
development  of  the  plants  treated  with  the  peat. 
On  taking  the  plants  from  the  pots  an  abundance  of 
root  is  characteristic,  there  being  a  striking  differ- 
entiation in  this  respect  between  the  plants  grown 
with  peat  and  those  grown  with  other  soil  mixtures. 
Another  feature,  commonly  noticed  with  variegated 
plants,  is  the  intensification  of  the  variegation  which 
is  comparable  with  that  noticed  in  the  colours  of 
the  flowers.  This  has  proved  one  of  the  unexpected 
results  of  treatment  with  peat.  Both  foliage  and 
blooms  are  often  richer  in  tone,  the  improvement  in 
foliage  emphasizing  and  reinforcing  that  obtained 
on  the  blooms.  An  increased  sturdiness  of  the 
stems  may  be  regarded  as  being  naturally  connected 
with  the  general  symmetrical  growth  of  the  treated 
plants,  but  in  several  instances  it  is  strikingly 
marked,  notably  at  Kew  in  the  case  of  the  cotton 
and  tobacco  plants.  Generally,  also,  the  plants  are 
larger  and  tend  to  mature  earlier. 

While  writing  the  present  volume  I  took  advantage 


144  THE  SPIRIT  OF  THE  SOIL 

of  an  invitation  from  Mr.  Robert  Holmes,  of  Tucks- 
wood  Farm,  Norwich,  to  visit  some  experiments  he 
has  been  conducting  with  the  bacterized  peat.  His 
gardens  cover  a  large  area  of  ground,  and  are  devoted 
chiefly  to  the  growing  of  sweet  peas  and  tomatoes, 
but  this  year,  particularly  as  a  consequence  of  the 
war,  potatoes  have  also  been  grown  on  a  considerable 
scale,  and  a  fair  number  of  small  parcels  of  ground 
have  been  laid  down  for  the  experimental  raising  of 
beet,  mangel-wurzels,  sugar-beet,  etc. 

Unfortunately,  a  single  factor,  the  persistent  dry 
weather  of  the  spring,  has  so  far  made  several  of  the 
results  obtained  of  little  value,  as  will  be  realized 
when  it  is  stated  generally  that  in  several  of  the 
fields  it  was  not  possible  to  detect  the  slightest  differ- 
ence between  crops  that  had  been  grown  in  ordinary 
soil  and  those  grown  beside  them,  which  had  received 
extra  treatment  with  farmyard  manure. 

In  the  glass  houses  devoted  to  tomato-growing, 
where  the  plants  have  been  treated  under  the  best 
known  conditions,  the  effect  of  humogen  has  been 
so  striking  that  even  the  amateur  can  tell  at  a  glance 
which  of  the  pots  have  received  dosage  with  humogen 
and  which  have  been  grown  under  strictly  com- 
parable conditions,  except  for  the  non-addition  of 
the  humogen.  Four  groups  of  experiments  in  all 
were  tried.  Five  pots  received  ordinary  soil  alone, 
five  received  soil  and  manure,  five  received  soil  and 
humogen,  and  five  soil,  manure,  and  humogen.  In 
all  cases  the  plants  were  strong  and  healthy,  and 
had  fruited  well,  but  those  treated  with  humogen 
were  taller  plants  than  the  others ;  their  leaves,  which 


I 


FIG.  9 

The  tomato  plant  above  is  representative  of  a  group  grown 
from  the  seedling  stage  with  the  aid  of  humogen.  The 
darker  fruits  at  the  base  of  the  plant  had  ripened  at  a 
time  when  only  one  or  two  fruits  on  the  untreated  were 
beginning  to  redden.  The  treated  plants  averaged  about 
sixteen  pounds  of  fruit  per  plant,  that  ripened  from  three 
weeks  to  a  month  earlier.  (Note  yard  measure.) 
(Grown  by  Mr.  Holmes,  Tuckswood  Farm,  Norwich.) 


THE  TESTING  OF  HUMOGEN  145 

were  rather  smaller,  showed  the  peculiar  rich  bluish- 
green  tint  that  is  associated  with  vigorous  growth, 
and  in  the  case  of  the  humogen-treated  plants  there 
were  clusters  of  red  fruits,  while  on  the  others  the 
fruits  were  only  beginning  to  change  from  green  to 
red.  The  tomatoes  on  the  humogen-treated  plants 
were  indeed  over-ripe,  as  they  had  been  left  on  the 
plants  so  that  full  opportunity  might  be  given  for  a 
comparison  between  the  humogen-treated  plants  and 
the  others.  Also,  as  the  accompanying  illustration 
demonstrates,  the  humogen-treated  plants  showed  a 
greater  quantity  of  fruit  than  the  plants  not  treated. 
In  one  of  the  houses  near  to  the  tomato  houses  a 
somewhat  similar  experiment  had  been  conducted 
with  the  Guernsey  Runner  Bean.  In  this  case 
humogen-treated  beans  have  made  striking  progress 
both  in  growth  and  in  quantity  of  fruit.  They 
stood  several  inches  higher,  and  had  large,  well- 
formed  leaves,  showing  a  deeper  green  than  that  on 
the  plants  near  by.  From  both  groups  of  plants  pods 
had  been  pulled,  and  neither  group  had  as  yet 
finished  fruiting.*  Already  there  had  been  a  marked 
increase  in  yield ;  the  humogen-treated  plants  showed 

*  While  this  book  was  going  through  the  press  a  report  was 
received  from  Mr.  Holmes  giving  the  weights  of  beans  pulled 
from  two  typical  plants.  They  are — 

Plant  grown  Plant  grown 

with  Humogen.       without  Humogen. 
Lbs.    Ozs.  Lbs.   Ozs. 

June  30 o     13^  o  15^ 

July  ii  ..          . .          . .     o     12!  o  y| 

July  23 i     13!  o  i| 

August  4  . .          . .          ..14  i  o 

Total         ..          . .     4     ii  J  2       8£ 


146  THE  SPIRIT  OF  THE  SOIL 

signs  of  improving  their  present  lead;  already 
2  ounces  more  of  pods  had  been  pulled  from  the 
treated  than  from  the  untreated  plants,  and  their 
increased  vigour  was  manifest. 

A  chance  experiment  conducted  casually  outside 
one  of  the  houses  gave  an  astonishing  result.  Mr. 
Holmes  told  me  that  he  remembered  reading  some 
years  ago  of  some  French  experiments  in  which 
ordinary  moss  had  been  used  as  a  medium  for 
growing  plants,  while  the  plant  food  had  been  sup- 
plied in  the  form  of  liquid  manure.  It  had  occurred 
to  him  that  it  would  be  interesting  to  try  the  effect 
of  growing  potatoes  in  moss,  moistened  from  time 
to  time  with  the  water  extract  of  humogen.  He 
planted  four  potatoes  in  sterilized  moss  in  a  shallow 
box,  I5-J-  inches  long,  6  inches  wide,  and  4  inches 
deep.  No  special  care  was  given  to  the  potatoes. 
As  a  start  the  moss  was  soaked  in  humogen  extract ; 
they  were  watered  from  time  to  time,  and  occasion- 
ally were  sprinkled  with  the  water  extract  of 
humogen.  The  box,  as  we  saw  it,  showed  a  luxuriant 
growth  of  leaves  standing  about  a  foot  from  the 
level  of  the  box,  but  when  the  plants  were  pulled 
the  roots  were  found  to  be  crowded  with  tubers, 
several  being  of  considerable  size,  and  the  majority 
being  still  immature.  Their  total  weight  was 
2  pounds  io£  ounces,  all  contained  in  an  area  of  a 
fifth  of  a  cubic  foot. 

Most  of  the  field  experiments  here  this  year  at  the 
time  of  writing  are  inconclusive,  for  the  crops  have 
not  yet  been  dug  up.  In  several  instances,  how- 
ever, it  was  possible  to  appreciate  at  a  glance  that 
the  potatoes,  sugar-beet,  etc.,  which  had  been 


<U    o 

§1 


t!  £      Z 

|  *       £ 

|l      ^ 

o   W1 

O      3  •*->    u     «« 


hi  I 

C-|  x° 

3|  >,  - 

=  S-s  s 


it 

o  t:  «i 


THE  TESTING  OF  HUMOGEN  147 

treated  with  the  peat,  were  markedly  superior  to 
those  which  had  not  received  treatment. 

Mr.  Holmes's  experiments  were  interesting  for 
another  reason.  There  was  a  single  field  of  potatoes 
— the  whole  was  a  markedly  poor  crop — one  large 
corner  of  which  had  been  treated  with  humogen,  but 
had  otherwise  received  exactly  the  same  manure  as 
the  rest  of  the  field,  and  to  the  eye  the  crop  on  this 
area  was  markedly  inferior  to  that  on  the  rest  of  the 
field.  It  is  the  first  instance  that  I  have  met  with 
personally  in  which  apparently  the  treatment  with 
humogen  has  retarded  growth.  The  soil  is  now 
being  analyzed  and  the  other  conditions  studied  to 
find  out  why  this  unusual  result  should  have  been 
obtained.*  That  the  treated  peat  of  itself  can  do 
harm  is  impossible,  as  plants  have  been  planted  in 
pure  humogen  and  done  well.  It  is  possible  that 
the  plot  may  improve  before  the  potatoes  are  dug 
up,  but  the  fact  remains  and  has  to  be  faced  that 
there  is  a  prima  facie  case  here  that  there  may  be 
certain  rare  soil  conditions  other  than  mere  acidity 
which  will  need  correction  before  humogen  can  be 
successfully  applied.  It  has  to  be  remembered  that 
the  present  season  has  been  abnormal,  and  that  the 
lesson  it  teaches  is  that  it  is  advisable  to  dig  the 
humogen  into  the  soil  early  in  the  year  at  a  time 
when  the  chance  of  drought  has  not  to  be  feared. 

As  will  be  seen  from  Appendix  B,  there  are  many 
other  places  where  experiments  have  been  made  with 

*  While  the  book  was  going  through  the  press  I  heard  from 
Mr.  Holmes  that  with  the  advent  of  an  ample  rainfall  the  plot 
improved,  and  now  (September  3)  at  least  equals  any  other 
portion. 


148  THE  SPIRIT  OF  THE  SOIL 

the  treated  peat.  There  is  only  one  other  garden, 
however,  that  I  have  been  able  to  find  time  to  visit 
while  writing  this  book,  a  market  garden  kept  by  the 
well-known  horticultural  writer,  Mr.  John  Weathers, 
at  Isle  worth.  The  conditions  under  which  he  has 
had  to  conduct  his  experiments  have  not  been  very 
favourable  to  the  peat,  as  in  most  cases  it  could  not 
be  delivered  to  him  until  the  plants  were  already 
in  the  ground.  In  such  circumstances,  combined 
with  the  drought,  he  obtained  only  negative  results 
by  top-dressing  in  the  case  of  bulbous  plants.  With 
Marguerite  daisies,  however,  a  striking  and  valuable 
result  was  obtained.  His  crop  generally  was  top- 
dressed  with  the  peat,  but  there  was  one  portion  of 
ground  in  which  he  was  able  to  dig  in  the  humogen  in 
the  quantity  of  2  J  ounces  to  the  square  yard.  Mar- 
guerites were  planted  in  this,  and  though  they  were 
planted  later  than  the  others,  they  flowered  a  week 
earlier. 

With  Pyrethrum  the  peat  gave  excellent  results. 
By  May  25  the  treated  plants  were  being  cut,  while 
by  June  4  cutting  had  not  commenced  on  the  plants 
which  had  not  been  treated.  Lily  of  the  Valley 
responded  well  to  treatment,  while  Forget-me-nots 
bloomed  in  greater  abundance  when  treated  with 
the  peat  and  compared  with  untreated  beds.  On 
Rhubarb  the  rows  receiving  humogen  were  con- 
siderably in  advance  of  a  row  that  was  left  un- 
treated. Apart  from  the  experiments  on  wheat, 
described  in  the  chapter  on  General  Results,  the 
most  striking  of  Mr.  Weathers's  results  were  those 
he  obtained  with  some  cabbages.  The  peat  was 
a  plied,  i  ounce  to  the  square  yard,  to  a  plot  of 


THE  TESTING  OF  HUMOGEN  149 

ground  in  which  the  throw-outs  from  another  bed 
were  planted.  At  the  start  the  cabbages  were 
miserably  weakly  plants.  Under  humogen  treat- 
ment, however,  they  picked  up  well,  and  though  they 
matured  rather  later,  there  was  in  the  end  nothing  to 
choose  between  the  originally  weakly  plants  after 
the  treatment  with  humogen,  and  those  cultivated 
along  ordinary  lines. 

In  discussing  the  results  generally  Mr.  Weathers 
emphasized  to  me  the  importance  of  digging  in  the 
humogen  instead  of  merely  using  it  as  a  top-dressing, 
but  there  was  no  doubt  left  in  his  mind  as  to  the 
marked  improvement  to  be  obtained  through  a  use 
of  the  peat,  both  in  the  increase  of  the  crop  and  in 
the  early  maturing  of  it. 

In  the  short  space  available  in  this  chapter  I  have 
tried  to  indicate  the  basis  on  which  the  case  for 
humogen  stands.  Both  from  the  laboratory  stand- 
point and  from  the  standpoint  of  the  grower  under 
glass  the  value  of  humogen  as  a  routine  method  of 
treatment  seems  to  me  definitely  established.  The 
experiments  made  to  extend  the  use  of  humogen  to 
field-work  on  a  large  scale  are  extremely  encouraging, 
and  at  present  there  seems  no  reason  to  doubt  that, 
when  suitably  applied,  results  comparable  with 
those  got  in  the  laboratory  and  greenhouse  will  be 
obtained  in  the  field.  If  this  result,  however,  is  to 
be  obtained  rapidly,  the  co-operation  of  the  farmers 
and  the  farming  stations  throughout  the  country  is 
essential,  as  it  is  only  by  extensive  experiments  care- 
fully carried  out  that  the  conditions  necessary  for 
the  best  results  will  be  satisfactorily  determined. 


CHAPTER  XI 

THE  PREPARATION  OF  HUMOGEN 

mportance  of  cost  and  availability  of  humogen — The  works  at 
Greenford  Green — Railway  facilities — The  raw  material — 
Incubating  with  humating  organisms — Sterilizing  the  peat — 
Inoculation  with  Nitrogen-fixing  organisms — New  system 
of  sterilization — Project  for  rapid  drying — Possibilities  of 
extension — Price  as  compared  with  manure. 

IN  the  course  of  the  discussion  on  a  paper  read  by 
Professor  Bottomley  before  the  Royal  Society  of 
Arts  on  "The  Bacterial  Treatment  of  Peat/'  Dr. 
J.  A.  Voelcker  said  that  from  a  practical  point  of 
view  the  cost  of  the  material  was  paramount,  and  he 
asked  the  question  whether  there  was  any  likelihood 
of  the  material  being  put  on  the  market  in  an  acces- 
sible form.  In  the  eighteen  months  which  have 
elapsed  since  the  date  of  the  reading  of  that  paper, 
the  situation  as  regards  the  bacterized  peat  has 
changed  very  materially.  Two  seasons  of  experi- 
ments have  confirmed  the  results  that  were  then 
announced,  and  the  peat  is  already  being  manu- 
factured on  an  experimental  scale.  While  the  whole 
story  of  soil  inoculation  and  of  the  auximones  is 
keenly  interesting  for  its  own  sake,  in  so  far  as  it 
throws  fresh  light  on  the  nature  and  mechanism 
of  plant  growth,  from  the  national  standpoint  at 
any  rate,  and  from  that  of  the  practical  grower,  the 

150 


THE  PREPARATION  OF  HUMOGEN       151 

essential  considerations  are,  firstly,  whether  the  use 
of  humogen  will  increase  the  yield  of  the  crop  to  the 
extent  that  is  believed  will  be  the  case  by  those 
responsible  for  its  production,  and,  secondly,  how 
far  the  grower  can  rely  on  getting  the  peat  in  the 
quantity  he  requires  at  a  reasonable  cost.  The 
preceding  chapters  in  this  book  constitute  the 
answer  to  the  first  of  these  questions,  and  it  is  for 
those  who  are  not  satisfied  with  the  evidence  brought 
forward  to  conduct  further  experiments  for  them- 
selves on  their  own  land. 

To  furnish  an  answer  to  the  second  question,  I 
have  visited  the  factory  at  Greenford  Green,  near 
Harrow,  partly  to  see  how  the  process  of  preparing 
the  peat  is  conducted  in  bulk  and  partly  to  deter- 
mine how  far  it  would  be  possible  to  increase  the 
output  to  meet  a  large  demand.  The  factory  where 
the  raw  peat  is  changed  into  humogen  is  situated  on 
six  acres  of  ground,  and  occupies  the  old  buildings 
used  by  Sir  William  Perkins  for  his  dye-works.  So 
far  only  a  fraction  of  the  ground  is  employed,  and 
the  old  chimney-stacks  are  still  standing  as  a  relic 
of  the  great  industry  which,  partly  as  a  result  of  the 
attitude  of  the  Government  towards  science,  and 
partly  owing  to  the  national  apathy,  has  been 
developed  into  a  world-wide  industry  by  Germany. 
Both  for  rail  and  water  transport  the  factory  is 
admirably  situated.  It  is  well  served  by  the  Grand 
Junction  Canal  and  both  the  Great  Central  and  the 
Great  Western  Railways. 

The  peat  is  brought  to  the  works  in  the  large  bales 
most  familiar  to  the  general  public  as  the  way  in 


152  THE  SPIRIT  OF  THE  SOIL 

which  the  peat  is  distributed  to  stables  as  peat -moss 
litter,  and  on  arrival  is  broken  up  and  stored  at  one 
end  of  a  large  shed.  Water-heated  pipes  pass 
through  half  a  dozen  bays,  and  into  these  the  peat  is 
thrown  when  it  has  been  moistened  and  thoroughly 
well  impregnated  with  the  aerobic  bacteria  which 
change  the  insoluble  Humic  acid  of  the  peat  into 
the  soluble  humates  required,  both  as  a  bacterial 
and  as  a  plant  food.  The  peat  lies  in  these  bays  for 
about  ten  days,  remaining  all  the  time  at  the  tem- 
perature which  is  best  suited  for  the  development  of 
the  bacteria.  During  the  process  it  tends  to  settle 
down.  It  darkens  in  colour,  but  otherwise  there  is 
to  the  unaided  senses  no  sign  of  any  change  taking 
place.  Notably  the  whole  process  occurs  without 
the  development  of  any  smell.  Close  to  the  bays 
the  large  boiler  is  situated.  It  is  designed  to  carry 
an  8o-pound  pressure  of  steam.  The  steam  from  it 
passes  through  pipes,  and  ends  in  two  large  water- 
jacket  cauldrons  of  the  type  used  in  melting  tallow. 
It  is  set  free  in  these  cauldrons  through  holes  pierced 
in  the  pipes  to  insure  that  the  steam  shall  thoroughly 
saturate  the  peat.  Once  this  has  been  fed  into  the 
cauldrons  steam  is  applied  to  them  for  a  period  of 
about  an  hour,  a  period  that  has  proved  sufficient 
to  insure  the  death  of  all  the  humating  organisms. 

From  the  cauldrons  the  peat,  now  sterile  and  rich 
in  plant  foods,  is  removed  to  another  shed,  where  it 
is  impregnated  with  Nitrogen-fixing  organisms, 
Bacillus  radicicola  and  Azotobacter  chroococcum. 
These  require  only  a  short  time  to  develop  in  the 
fertile  sterilized  peat,  and  this  is  then  spread  on  the 


THE  PREPARATION  OF  HUMOGEN       153 

floor  in  heaps  and  air-dried.  As  soon  as  it  is  dried 
it  is  packed  in  bags  and  is  ready  for  use. 

Such  is  the  process  as  it  has  been  worked  for  some 
time  now  at  Greenford  Green.  The  description,  how- 
ever, only  gives  a  slight  idea  of  what  has  been  done. 
While  I  was  at  the  works,  an  experiment,  suggested 
by  Mr.  Holmes  of  Tuckswood  Farm,  Norwich,  as  a 
result  of  the  work  he  has  done  in  sterilizing  soil,  was 
in  progress.  It  appears  to  be  practicable  to  avoid 
the  use  of  the  cauldrons  for  sterilizing  the  peat  and 
to  substitute  for  them  a  rough  frame  which  lies  on 
the  ground,  and  carries  his  patent  "  norvic  "  cover. 
Steam  on  being  applied  to  this  Hght  frame,  so  far  as 
the  experiments  have  gone,  is  able  effectively  to 
sterilize  the  peat,  and  if  the  process  on  further  ex- 
periment proves  satisfactory,  there  will  be  a  con- 
siderable saving  of  labour  and  space,  and  an  increase 
of  convenience  in  the  handling  of  the  peat. 

Already  in  view  of  the  increased  demand  a  machine 
is  in  course  of  installation  which  at  first  sight 
resembles  a  tubular  boiler.  There  are  steam  com- 
partments at  either  end,  and  a  large  number  of  pipes 
running  between  them .  The  proposal  is  to  mount  this 
apparatus  and  to  keep  it  revolving  while  the  prepared 
and  inoculated  peat  is  being  automatically  shovelled 
against  the  warm  pipes,  a  method  that  would  greatly 
shorten  the  time  necessary  for  the  whole  operation, 
and  facilitate  the  very  difficult  process  of  drying. 

I  have  been  at  pains  to  describe  the  system 
employed  to  prepare  the  peat  at  some  length,  as  it  is 
clear  from  the  description  that  the  present  rate  of 
manufacture  could  be  very  greatly  extended.  For 


154  THE  SPIRIT  OF  THE  SOIL 

the  time  being  only  a  portion  of  one  of  the  sheds  is 
being  used,  but  there  would  be  no  difficulty  in 
meeting  an  increased  demand  at  once  by  duplicating 
or  triplicating  the  present  plant.  Hitherto  it  has 
not  seemed  desirable  to  manufacture  on  a  large  scale, 
as  the  work  at  the  factory  has  as  yet  been  only 
experimental.  Various  samples  of  peat  are  con- 
tinually being  tested,  as  experience  shows  that 
different  samples  of  peat  show  large  differences  in 
the  quantity  of  soluble  humus  that  they  yield,  and 
it  has  been  thought  better  to  carry  through  the 
necessary  preliminary  work  on  a  small  scale  before 
fitting  up  a  plant  which  might  prove  better  or  worse 
suited  to  the  particular  quality  of  peat  ultimately 
adopted  as  the  standard. 

As  regards  cost  it  is  difficult  to  state  anything 
definitely.  While  the  process  was  in  the  experi- 
mental stage  the  price  of  the  peat  was  provisionally 
fixed  at  155.  for  3  bushels.  This  price  was  fixed 
arbitrarily  to  meet  the  convenience  of  those  who 
wished  to  conduct  experiments,  but  there  is  reason 
to  believe  that  when  the  substance  is  dealt  with 
commercially  a  price  will  be  practicable  at  con- 
siderably less  than  £10  per  ton.  For  purposes  of 
comparison  with  ordinary  fertilizers  it  may  be 
assumed,  for  the  moment  therefore,  that  the  cost  of 
it  is  about  £10  per  ton.  In  view  of  the  fact  that  the 
available  plant  food  in  peat,  as  compared  with  that 
in  rotted  stable  manure,  is  as  between  fifty  and 
eighty  to  one,  the  superiority  of  the  peat  from  the 
standpoint  of  its  food  value  alone,  when  considered 
in  relation  to  its  cost,  is  strikingly  apparent. 


CHAPTER  XII 

PRESS  AND  OTHER  CRITICISM 

Early  hostile  criticism — Lines  of  attack — Sound  basis  of  criticism 
— Need  for  experiment — Growth  of  opinion  in  favour  of 
inoculation — Support  from  the  Board  of  Agriculture — 
Royal  Society  of  Arts  meeting — Two  opinions  of  experts — 
Press  criticisms. 

THERE  has  been  no  lack  of  criticism  of  the  work  done 
by  Professor  Bottomley  on  Nitrogen-fixing  organ- 
isms. Of  this  it  is  possible  for  me  to  speak  person- 
ally with  some  authority,  as  it  has  been  my  business 
as  a  journalist  ever  since  the  earliest  publications 
were  made  on  the  subject,  not  only  to  keep  in  touch 
with  the  various  stages  of  the  work  in  King's  College 
Laboratory,  but  to  make  inquiries  of  agricultural 
experts  and  others  as  to  their  opinion  of  the  work. 
I  have  also  from  time  to  time  attended  not  only 
popular  meetings  where  the  method  has  been  ex- 
plained, but  also  scientific  meetings  where  the  views 
put  forward  have  been  discussed  by  critical 
audiences. 

In  the  earlier  years  I  heard  a  great  deal  of  hostile 
criticism;  it  was  criticism  of  the  sort  that  is  in- 
valuable to  the  journalist,  given  to  him  in  confidence 
for  the  guidance  of  his  paper.  I  was  advised  repeat- 
edly to  be  very  cautious  in  what  I  wrote;  I  was 

55 


v 


156  THE  SPIRIT  OF  THE  SOIL 

warned  of  the  extreme  difficulty  of  field  experiments. 
It  was  pointed  out  to  me  that,  even  when  every  care 
was  taken  to  give  the  whole  of  a  field  identical  treat- 
ment, such  a  field,  if  divided  into  plots,  would  yield 
returns  from  certain  plots  that  would  vary  by  as 
much  as  50  or  i oo  per  cent,  from  the  mean,  and  that 
long-continued  experiment,  therefore,  was  necessary 
before  the  results  claimed  for  soil  inoculation  could 
be  accepted.  Professor  Bottomley,  I  was  told  very 
truly,  was  an  enthusiast  with  more  laboratory  than 
field  experience,  and  might  have  been  misled  by 
results  apparently  due  to  the  bacteria,  but  due  in 
reality  to  other  causes  of  which  he  had  no  know- 
ledge. Facts  and  figures  were  quoted  to  me  showing 
how  frequently  in  the  past  generalizations  have  been 
made  by  men  of  science  in  connection  with  agri- 
culture on  insufficient  experiments,  and  that  the 
result  has  been  disappointment  and  the  discrediting 
of  science  among  practical  farmers. 

Experience  has  shown  that  there  was  real  wisdom 
underlying  these  criticisms.  From  the  standpoint 
of  the  practical  man  nitrobacterine  was  a  failure, 
because  it  was  not  realized  that  certain  conditions 
were  essential  for  its  successful  application.  Scien- 
tifically, however,  it  was  a  success,  as  is  proved  by  the 
fact  that  after  seven  years  of  experiment  the  Ameri- 
can Board  of  Agriculture  is  distributing  a  similar  pre- 
paration to  farmers  and  recommending  its  use. 

As  against  the  criticisms  I  heard,  there  were  the 
results  that  were  obtained.  The  laboratory  experi- 
ments proved  conclusively  that  under  controlled 
conditions  nitrobacterine  gave  results  of  an  order 


PRESS  AND  OTHER  CRITICISM  157 

that  could  be  obtained  by  no  other  means.  The 
reports  received  from  growers  showed  that  there 
were  instances,  too  many  to  be  accounted  for  by 
chance,  in  which  results  of  the  same  order  as  those 
gained  in  the  laboratory  were  obtained,  but  under 
glass  and  in  the  field.  I  considered  then,  as  I  con- 
sider still,  that  it  was  desirable  in  the  interests  of 
agriculture  that  extensive  field  experiments  should 
have  been  carried  out  by  farmers,  as  the  evidence 
indicated  that  in  nitrobacterine  there  was  a  new 
means  available  for  increasing  the  returns  that  could 
be  won  from  the  soil,  and  that  it  was  only  by  experi- 
ments conducted  on  a  large  scale  that  it  would  be 
possible  to  determine  the  best  conditions  for  its  use. 
Seven  years  have  gone  by  since  nitrobacterine  was 
tested  on  at  all  a  considerable  scale,  and  during  that 
period  there  has  been  a  marked  change  in  scientific 
opinion.  There  is  still  scepticism  in  many  quarters, 
but  whereas  in  the  early  days  Professor  Bottomley 
stood  almost  alone  in  this  country  in  advocating  the 
practical  use  of  inoculation,  he  has  to-day  a  con- 
siderable body  of  expert  opinion  that  is  with  him. 
Experience  with  nitrobacterine  has  resulted  in  what 
might  have  been  expected.  Certain  of  the  con- 
ditions necessary  for  successful  inoculation  are  now 
understood.  In  humogen  a  means  of  introducing 
the  bacteria  has  been  discovered,  which  very 
materially  reduces  the  risk  of  negative  results.  The 
Board  of  Agriculture  and  Fisheries  has  recognized 
the  value  of  the  work  by  making  a  grant  in  aid  of 
the  researches,  and  the  time  is  ripe  to-day  for  the 
conducting  of  experiments  on  a  large  scale.  To 


158  THE  SPIRIT  OF  THE  SOIL 

show  that  this  is  a  general  opinion  I  have  thought  it 
desirable  to  quote  here  a  couple  of  the  views  to 
which  experts  have  given  expression  during  the 
last  two  years,  and  also  to  quote  the  views  of  several 
leading  newspapers. 

At  a  large  meeting  held  early  in  1914  at  the  Royal 
Society  of  Arts,  Professor  Keeble,  F.R.S.,  who  was 
in  the  chair,  opened  the  discussion,  and  said  "he 
could  put  it  that  Professor  Bottomley  was  able  to 
take  material  of  small  commercial  value,  used 
mainly  for  the  making  of  fuel  and  oil,  and  extract 
from  it  not  only  the  humates  in  a  form  in  which 
they  could  be  used  for  plants,  but  also  to  use  these 
humates  as  a  seed  bed  in  which  the  Azotobacter,  a 
Nitrogen-fixing  organism,  could  thrive.  If  more 
extended  trials  than  those  so  far  undertaken  could 
establish  that  Professor  Bottomley  could  do  these 
two  things,  he  would  have  earned  the  encomium  of 
Swift  for  those  who  made  two  blades  of  grass  grow 
where  one  grew  before/' 

Dr.  O.  Rosenheim  said  "he  believed  that  bacterized 
peat  was  a  substance  having  remarkable  properties 
as  a  stimulant  to  growth.  He  had  himself  carried 
out  a  few  experiments  for  the  purpose  of  investi- 
gating the  minimum  quantity  of  the  peat  which 
would  produce  the  results  which  Professor  Bot- 
tomley had  shown;  the  quantity  proved  to  be  very 
small  indeed.  He  had  found  that  a  solution  pre- 
pared from  the  peat,  containing  only  about  30  milli- 
grammes of  solid  substances,  produced  striking 
results  on  plant  growth.  His  results  showed  that  the 
effect  of  peat  was  out  of  all  proportion  to  what 


I! 


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PRESS  AND  OTHER  CRITICISM  159 

would  be  expected  from  an  equal  weight  of  a  mere 
manurial  substance.  The  amount  of  Nitrogen  in  it 
could  not  supply  the  needs  of  the  plant,  and  that 
remark  was  equally  applicable  to  the  amount  of 
phosphates,  etc.,  present.  There  appeared  to  be 
some  fundamentally  new  substance  at  work,  a  sub- 
stance which  was  at  the  bottom  of  plant  growth.  It 
had  struck  him  that  the  active  principle  in  prepared 
peat  had  some  analogy  to  a  newly  discovered  factor 
of  animal  nutrition,  which  was  still  in  its  infancy. 
He  believed  that,  directly  or  indirectly,  the  plant 
obtained  what  it  required  from  the  humus,  and  that 
in  the  peat  as  prepared  by  Professor  Bottomley  the 
essential  substance  for  growth  was  present.  Of 
course  it  was  advisable  to  be  very  cautious  in  bring- 
ing forward  such  a  view,  but  the  experiments  so  far 
carried  out  seemed  to  support  it,  and  he  believed 
that  Professor  Bottomley's  bacterized  peat  con- 
tained in  relatively  large  quantities  a  substance  of 
fundamental  importance." 

Country  Life,  October  25,  1913. 

"  Professor  Bottomley's  results,  both  in  the  field 
and  the  laboratory,  have  been  extremely  good.  His 
prepared  peat  contains  over  fifty  times  as  much 
available  plant  food  as  farmyard  manure.  .  .  . 
There  is  no  doubt  that  the  prepared  peat  is  of  great 
value  as  a  manure ;  but  whether  its  fertilizing  action 
is  due  to  the  presence  of  Nitrogen-fixing  bacteria, 
or  merely  to  the  larger  quantity  of  soluble  humates 
produced  during  the  preparation  of  the  medium, 
cannot  yet  be  said  to  have  been  definitely  proved, 
while  the  peat  has  also  a  beneficial  mechanical 
action  on  the  soil.  If  only  the  product  can  be 


160  THE  SPIRIT  OF  THE  SOIL 

manufactured  at  a  reasonable  cost,  its  value  will  be 
immense  to  those  who  go  in  for  intensive  cultivation, 
to  market  gardeners,  to  horticulturists,  to  farmers, 
and  for  use  on  golf  greens." 

Eastern  Daily  Press,  May  8,  1915  (Mr.  F.  I.  Cooke). 

"  In  the  course  of  our  Bournemouth  experiments 
it  was  clear  to  me,  a  fairly  old  campaigner  in  manurial 
experiments,  scientifically  conducted,  that  there 
must  be  some  other  key  to  our  remarkable  results, 
and  to  the  far  more  extensive  ones  at  Kew  Gardens. 
All  who  are  scientifically  acquainted  with  the  sub- 
ject, and  have  studied  it  in  practice,  know  very  well 
that  amongst  the  foods  of  plants  the  only  one 
hitherto  shown  to  be  an  excessive  stimulant  is 
Nitrogen,  in  one  or  other  of  the  forms  in  which  it  is 
usually  applied.  The  various  manures  of  mineral 
origin,  such  as  phosphates,  potash,  etc.,  are  all  mild 
in  their  action,  tending  to  sound  and  steady  growth 
to  well-ripened  seed,  or  fruit  or  wood,  whilst  too 
much  Nitrogen  upsets  the  balance,  and  merely  tends 
to  sappy  growth  and  more  abundant  foliage  than 
can  be  properly  matured.  But  the  striking  feature 
of  our  experiments  with  the  peat  was  that  the  entire 
development  of  some  of  the  plants,  both  above  and 
below  ground,  was  almost  doubled  in  the  short 
period  of  six  weeks,  and  yet  was  perfectly  sound  and 
well  balanced.  I  felt  sure,  therefore,  that  some 
factor  previously  unknown,  other  than  the  excess  of 
Nitrogen,  provided  by  the  peat,  was  thus  indicated. 
I  do  not  mean  that  it  had  not  been  at  work  before, 
but  that  its  identity  as  a  separate  nutrient  had  not 
been  recognized  or  even  suspected  before.  Later 
developments  of  the  peat  investigations  have  appar- 
ently shown  this  conclusion  to  have  been  fairly  well 
justified.  The  Professor  was  perhaps  building  better 
than  he  knew,  and  was  on  the  track  of  an  accessory 


PRESS  AND  OTHER  CRITICISM  161 

plant  food  new  to  science,  and  one  which  in  addition 
to  its  extraordinary  scientific  interest,  may  prove  of 
very  great  practical  importance." 

The  Field,  May  21,  1914. 

;'  There  is  good  reason  to  think  that  Professor 
Bottomley  has  solved  the  problem  of  enhancing  the 
fertility  of  the  soil  by  the  application  of  bacterial 
cultures.  As  has  already  been  explained  in  the 
garden  department  of  the  Field,  peat  has  been 
utilized  as  the  medium  for  impregnating  the  land 
with  the  cultivated  bacteria,  and  the  results  at  Kew, 
the  Chelsea  Physic  Garden,  and  other  centres,  exceed 
even  the  expectations  of  the  inventor.  The  farmer 
is  not  entirely  dependent  upon  the  experiments  with 
garden  plants  for  his  appreciation  of  the  discovery. 
The  bacterized  peat,  as  the  preparation  has  been 
aptly  termed,  has  been  used  for  potatoes,  turnips, 
beet,  onions,  and  carrots,  and  the  effect  in  all  cases 
has  been  pronounced,  the  treated  peat  easily  sur- 
passing farmyard  manure  and  a  mixture  of  arti- 
ficials in  influencing  production.  The  average  in- 
crease in  potatoes  over  artificials  was  75  per  cent., 
and  over  dung  41  per  cent. ;  turnips,  47  per  cent,  and 
26  per  cent.;  beet,  54  per  cent,  and  53  per  cent.; 
onions,  no  per  cent,  and  46  per  cent.;  and  carrots, 
20  per  cent,  and  28  per  cent.  Most  of  these  crops 
are  of  chief  interest  to  the  market  gardener,  but  it 
may  be  assumed  that  the  material  will  be  similarly 
effective  upon  field  crops.  The  discovery  promises 
to  be  of  the  greatest  importance  to  intensive  culti- 
vators, whose  prosperity  has  been  menaced  by  the 
reduction  in  the  supplies  of  town  manure.  Mineral 
and  chemical  fertilizers  are  valuable  substitutes,  but 
a  vegetable  preparation  such  as  treated  peat  would 
be  attended  with  less  risk  of  ultimate  injury  to  the 
land.  The  preparation  will  not  be  put  upon  the 


162  THE  SPIRIT  OF  THE  SOIL 

market  until  its  qualities  have  been  thoroughly 
tested,  and,  of  course,  until  an  estimate  of  its  cost 
is  available  it  will  be  impossible  to  appraise  its 
value  as  an  agricultural  accessory.  The  prospect  at 
present,  however,  is  exceedingly  bright,  and  farmers 
will  do  well  to  watch  its  progress  and  developments 
during  the  coming  season.'' 

The  Field,  August  7,  1915. 

"  Humogen  is  the  name  given  to  what  has  hitherto 
been  known  as  bacterized  peat,  a  preparation  which 
Professor  Bottomley  has  made  famous  by  proving 
that  it  stimulates  plant  growth,  not  only  with 
respect  to  fatness  of  leaves  and  shoots,  but  also  with 
respect  to  the  free  development  of  flowers,  fruit,  and 
roots.  Exactly  what  it  is  that  causes  ordinary  farm 
and  garden  soil  to  become  so  exceedingly  fertile 
when  humogen  has  been  added  to  it  may  be  known 
to  Professor  Bottomley,  but  it  is  not  clear  to  the 
practical  cultivator,  who  understands  well  enough 
the  action  of  fertilizing  manures,  natural  and  arti- 
ficial, but  is  puzzled  by  the  stimulating  influence  of 
ordinary  peat  moss  to  which  nitrogen-fixing  bacteria 
have  been  added.  This  peat  before  treatment  is  of 
very  little  value  to  the  cultivator.  It  may  contain 
plant  food  as  well  as  the  humic  acid,  the  presence  of 
which  is  said  to  render  the  food  unavailable;  but 
assuming  that  the  whole  of  this  food  is  freed  by  the 
treatment  to  which  it  is  subjected  by  Professor 
Bottomley,  that  alone  would  not  account  for  the 
growth  made  by  the  plants  fed  with  it. 

"  It  appears  likely  that  we  are  on  the  track  of 
important  revelations  respecting  plant  food,  for  we 
are  assured  by  men  like  Dr.  Russell  that  the  text- 
books are  quite  wrong  on  the  subject.  What  culti- 
vated plants  really  require,  and  the  easiest  and 
best  way  to  supply  it,  are  questions  of  great  import- 


PRESS  AND  OTHER  CRITICISM  163 

ance,  the  answers  to  which,  according  to  the  most 
recent  investigations,  have  hitherto  been  misleading. 
Meanwhile  we  have  Professor  Bottomley's  highly  in- 
teresting experiments  with  bacteria  and  peat  or  peat- 
moss, showing  that  even  soils  which  are  considered 
to  be  worthless  for  agriculture  or  horticulture  con- 
tain a  rich  supply  of  plant  food  which  only  requires 
to  be  released  by  a  process  of  inoculation  to  produce 
abundantly.  Evidence  of  this  is  gradually  accumu- 
lating as  the  result  of  experiments  with  farm  and 
garden  crops  by  trustworthy  persons.  One  of  these 
is  Mr.  R.  Holmes,  Tuckswood  Farm,  Norwich,  to 
whom  we  are  indebted  for  the  two  photographs  here 
reproduced,  showing  the  influence  of  humogen  on 
the  potato  and  the  tomato. 

"  The  tomato  plant  is  a  sample  of  a  number  that 
were  grown  in  ordinary  garden  soil,  to  which  humogen 
had  been  added  in  the  proportion  of  one  in  eight.  As 
can  be  seen  in  the  photograph  (p.  146),  the  plant 
grew  vigorously,  but  did  not  develop  large  leaves, 
as  tomatoes  grown  with  ordinary  stimulating  foods 
generally  do.  On  the  other  hand,  it  bore  an  excep- 
tionally good  crop  of  well-formed  fruit,  which  ripened 
perfectly,  and  when  gathered  weighed  16  pounds. 

'  The  potato  plants  were  grown  in  a  wood  box, 
21  inches  by  6  inches  by  4  inches,  which  was  filled 
with  ordinary  wood-moss  that  had  been  steamed 
to  sterilize  it,  and  then  saturated  with  a  solution  of 
humogen.  Four  potato  sets  were  planted  in  this 
on  May  18,  and  the  box  was  placed  on  a  border  in 
the  open,  where  it  was  watered  weekly  with  the 
same  solution.  On  July  22 — that  is,  two  months 
after  planting — the  contents  of  the  box  were  exposed 
and  photographed.  The  new  potatoes  were  clean 
and  well  formed,  and  they  weighed  3  pounds.  No 
doubt  the  moss  contained  a  certain  quantity  of 
plant  food,  and  the  sterilizing  would  improve  it,  but 
no  experienced  cultivator  would  expect  to  get  a 


164  THE  SPIRIT  OF  THE  SOIL 

good  crop  of  potatoes  from  it,  and  we  must  therefore 
conclude  that  the  humogen  was  both  food  and 
stimulant. 

"  These  results  are  similar  to  those  obtained  pre- 
viously with  a  large  number  of  different  kinds  of 
plants  grown  in  pots,  for  which  humogen  was  used. 
So  far  as  we  understand  this  peat  preparation, 
nothing  is  added  that  would  be  called  a  manure, 
either  chemical  or  organic,  and  the  question  we 
would  like  to  ask  Professor  Bottomley  is,  would  any 
kind  of  soil  other  than  peat  or  peat -moss  be  similarly 
affected  by  his  treatment  ?  If  by  adding  certain 
bodies  to  peat  he  can  change  its  plant  food  properties 
so  enormously,  would  it  b$  possible  to  add  these 
bodies  direct  to,  say,  a  ten-acre  field  or  a  fruit 
orchard,  applying  it  as  guano,  for  example,  is 
applied  ?  Or  is  the  peat  an  essential  part  of  the 
fertilizer  ?" 

Gardeners'  Chronicle,  October  25,  1913. 

"  It  will  be  patent  to  everyone  that  if  it  should 
prove  possible  to  make  peat  plant  food  cheaply,  and 
if  further  trials  confirm  the  results  of  those  which 
have  been  made  at  Kew  and  elsewhere,  Professor 
Bottomley's  discovery  will  be  of  great  service  to 
horticulture  and  agriculture." 

Gardeners*  Chronicle,  March  21,  1914. 

"  Briefly  these  new  facts  are  that  extremely  small 
quantities  of  a  watery  extract  of  bacterized  peat  are 
potent  stimulators  of  plant  growth.  For  example, 
it  is  stated,  on  the  authority  of  Dr.  Rosenheim,  who 
carried  out  the  experiments,  that  plants  treated 
twice  with  the  water  extract  of  0*18  gramme 
( »  T^  ounce)  respond  very  readily  to  the  treatment, 
and  grow  away  from  untreated  '  control '  plants. 


PRESS  AND  OTHER  CRITICISM  165 

"  If  the  result  of  other  more  extended  and  similar 
experiments  is  to  confirm  the  correctness  of  this 
observation,  we  shall  be  face  to  face  with  a  discovery 
of  prime  importance,  for  it  is  wellnigh  certain  that 
this  growth-accelerating  effect  of  the  extract  cannot 
be  brought  about  by  the  nitrogenous  or  other 
ordinary  substances  contained  in  that  extract. 
The  actual  amounts  of  nitrogen — and  of  phosphorus 
— contained  in  T|^-  ounce  of  the  bacterized  peat 
must  be  extremely  small — far  too  small,  as  it  would 
seem,  to  produce  a  marked  increase  in  the  rate  of 
growth  of  plants  potted  in  ordinary  garden  soil." 

Gardeners'  Magazine,  October  3,  1914. 

"  Professor  Bottomley,  of  King's  College,  London, 
has  found  that  when  peat  has  been  subjected  to  the 
action  of  bacteria  it  becomes  transformed,  and  acts 
as  a  manure  of  considerable  value." 

Pall  Mall  Gazette,  June  6,  1914. 

"  The  whole  conception  of  the  growth  of  plants 
may  have  to  be  altered  as  the  result  of  some  im- 
portant experiments  that  have  been  made  at 
King's  College,  London,  and  since  submitted  to 
successful  tests  at  Kew  and  Chelsea.  Just  as 
modern  research  has  discovered  that  growing  animals 
cannot  get  the  full  value  out  of  pure  food,  and  will 
not  continue  to  grow  unless  there  is  some  trace  of 
what  is  termed  "  accessory  food  body"  used  with 
it,  so  it  is  thought  there  is  in  bacterized  peat  a  sub- 
stance similar  to  the  accessory  food  bodies  necessary 
for  growing  animals.  And  the  theory  is  that  plants, 
just  like  animals,  must  have  some  of  this  substance, 
otherwise  they  will  not  be  able  to  utilize  the  food 
material  in  the  soil.  .  .  .  Some  very  striking  results 
have  been  obtained  with  barley.  Seven  is  usually 


166  THE  SPIRIT  OF  THE  SOIL 

the  maximum  number  of  shoots  from  barley  plants 
manured  in  the  ordinary  way.  With  bacterized 
peat,  however,  as  many  as  eighteen  have  been 
obtained.  This  means  that  instead  of  seven  ears 
there  would  be  eighteen  to  every  seed  originally 
planted." 

The  Times,  October  7,  1913,  and  May  21,  1914. 

"  Agriculture's  debt  to  science  is  already  large, 
but  '  bacterized  peat ' — a  new  stimulant  of  plant 
life  produced  at  King's  College,  London,  by  Pro- 
fessor W.  B.  Bottomley — promises  to  make  the  debt 
incalculably  larger. 

"  Tomatoes  of  quite  a  respectable  size  have  been 
grown  from  seeds  set  in  pure  sand,  and  watered  with 
an  extract  of  this  product.  An  eggcupful  sprinkled 
on  the  surface  of  the  soil  doubled  the  size  of  arum 
lilies;  carnations  inoculated  with  eel-worm  shook 
off  the  pest  with  the  aid  of  the  '  peat,'  and  plants 
of  every  kind  grew  more  strongly,  flowered  more 
profusely  and  with  intensified  colours,  and  quickly 
became  pot  -  bound  through  root  -  development. 
Equally  striking  results  have  been  obtained  with 
barley,  wheat,  and  oats. 

"  The  evidence  already  obtained  in  regard  to  the 
efficacy  of  this  new  manure  is  reassuring.  It  has 
been  subjected  to  severe  tests  in  the  open  fields  as 
well  as  in  the  laboratory,  and  in  every  instance  its 
effect  has  been  pronounced.  Professor  Bottomley's 
estimate  of  its  value  is  more  than  confirmed  by 
those  who  have  co-operated  with  him  in  practical 
experiments  under  different  sets  of  conditions  and 
with  different  crops.  Chemical  analyses  of  the  pre- 
pared peat  show  that  it  contains  over  fifty  times  as 
much  available  food  material  as  farmyard  manure- 
that  is  to  say,  i  ton  of  the  prepared  peat  is  superior 
to  50  tons  of  farmyard  manure.  This  is  a  bold 


FIG.    13 

Eel-worm  is  a  serious  disease  in  many  plants,  but  carnations  are  especially 
liable  to  it.  Both  the  carnations  shown  above  (typical  specimens  of  a 
group  experiment)  were  potted  in  soil  known  to  be  infected,  with  the 
object  of  testing-  whether  humogen  gave  resistant  powers  to  the 
plant.  The  humogen-treated  carnation,  although  infested  in  the 
early  stages,  gradually  grew  away  from  the  pest  and  developed  into 
a  perfect  plant.  The  untreated,  although  receiving  various  stimu- 
lating plant-foods,  reached  the  stage  shown  and  then  collapsed. 
(The  Royal  Gardens,  Kew.) 


PRESS  AND  OTHER  CRITICISM  167 

claim  to  make,  but  it  is  based  upon  practical  demon- 
stration, and  has  not  merely  a  laboratory  justi- 
fication. 

'  While  the  discovery  is  of  more  immediate 
importance  to  horticulturists  and  market  gardeners, 
it  is  also  of  great  interest  to  farmers.  Should 
present  expectations  be  fulfilled,  it  would  prove  of 
great  service  to  those  engaged  in  any  form  of  inten- 
sive culture.  The  primary  need  of  the  intensive 
cultivation  is  an  organic  manure.  The  market  is 
fairly  well  supplied  with  salts  or  minerals,  natural 
or  by-products,  but  it  has  been  found  that,  although 
these  materials  are  useful,  they  cannot  take  the  place 
of  a  good  organic  fertilizer.  The  need  of  a  new 
vegetable  manure  is  emphasized  by  the  great 
reduction  in  the  quantity  of  town  manure  available, 
owing  to  the  substitution  of  motor  power  for  horses 
in  street  traffic.  The  market  gardening  industry  at 
a  critical  time  in  its  development  has  suffered  a 
severe  loss  by  the  reduction  in  the  supply  of  town 
manure.  Horticulture  in  its  diversified  forms,  from 
the  smallest  suburban  plot  to  the  Royal  Botanic 
Gardens  at  Kew,  has  shared  in  the  resulting  dis- 
abilities; and  although  recourse  has  been  had  to 
artificial  materials,  the  chief  effect  has  been  to 
demonstrate  the  serious  disadvantage  at  which 
intensive  culture  is  placed  without  an  adequate 
supply  of  organic  manure.  The  keen  interest  shown 
in  Professor  Bottomley's  treated  peat  reflects  the 
measure  of  the  need  of  something  to  supplement  the 
diminishing  quantities  procurable  from  London  and 
other  towns. 

"  As  every  farm  is  a  producer  of  organic  manure 
in  greater  or  less  quantity,  the  need  is  not  so  pressing 
in  agriculture  as  in  horticulture.  It  would  be  a 
great  gain  for  the  former,  however,  if  the  supply  of 
home-made  dung  could  be  added  to  in  so  simple  a 
form  as  that  prepared  by  Professor  Bottomley. 


168  THE  SPIRIT  OF  THE  SOIL 

There  are  few  who  have  as  much  as  they  could  use 
to  advantage,  with  the  result  that  they  have  either 
to  apply  it  sparingly  or  rely  entirely  on  artificials  for 
a  portion  of  the  green  crop  and  grass  areas.  Its 
action  being  quicker  than  that  of  dung,  it  might  be 
thought  that  its  stimulating  energy  was  largely 
expended  in  the  first  year.  Recent  tests  made  in 
the  laboratory,  however,  show  that  the  treated 
Kew  soil  after  a  season's  growth  still  contains  a  large 
amount  of  available  food  material,  and  that  the 
nitrogen-fixing  bacteria  are  still  active  and  capable 
of  producing  further  nitrogenous  plant  food.  Ex- 
perience alone  can  decide  this  and  other  important 
points,  but  in  the  meantime  it  is  satisfactory  to  have 
evidence  that  an  important  addition  is  likely  to  be 
made  to  our  resources.  It  is  interesting  to  know 
that  there  is  virtually  no  limit  to  the  production  of 
the  material.  If  there  is  any  limitation  it  is  in  the 
quantity  of  the  moss  available,  since  the  bacterial 
cultures  are  capable  of  indefinite  multiplication." 


CHAPTER  XIII 

HOW  HUMOGEN  IS  APPLIED 

How  humogen  is  applied — Humogen  suitable  for  all  soils  and  all 
crops — Analogy  with  air,  carbon  dioxide,  and  water — Im- 
portance of  aeration  of  soil  and  of  presence  of  lime — Evils 
of  acidity — Test  for  presence  of  lime — Humogen  in  field 
work.  With  herbaceous  flower  borders.  With  pot  plants. 
With  grass — Liquid  extract  of  humogen — Humogen  used 
with  other  fertilizers — Humogen  and  monocotyledons — 
Humogen  in  agriculture — Its  mixture  with  farmyard 
manure — Results  to  be  expected. 

IN  the  course  of  previous  chapters  it  has  been  an 
easy  matter  to  demonstrate  the  reasonableness  of 
the  view  that  humogen  is  a  substance  suitable  for 
all  plants  and  for  all  soils.  Hitherto  I  have  not 
insisted  on  the  point,  as  by  stating  the  facts  con- 
nected with  humogen,  and  explaining  the  mechanism 
of  its  working,  I  have  been  confident  that  the  con- 
clusion would  inevitably  suggest  itself  to  the  minds 
of  all  readers.  At  first  sight  the  statement  is  apt 
to  be  startling,  and  it  is  always  so  inevitably  when 
made  to  those  who  have  not  a  clear  idea  as  to  the 
nature  of  humogen.  It  becomes  more  intelligible 
when  one  remembers  that  in  adding  humogen  to  the 
soil  one  is  doing  nothing  more  than  assisting  Nature . 
Humus  of  a  better  or  worse  quality  is  universally 
present  in  all  cultivated  soils;  the  bacteria  which 

169 


170    1        THE  SPIRIT  OF  THE  SOIL 

effect  the  Nitrogen  reactions  are  to  be  found  either 
themselves  or  replaced  by  similar  ones  in  all  soils  in 
which  vegetation  is  growing,  and,  as  in  the  peat,  so 
in  untreateds  oil,  they  are  to  be  found  fixing  Nitrogen 
and  giving  rise  to  the  necessary  auximones.  All  that 
the  humogen  does  in  essence  is  to  furnish  the 
healthiest  possible  strain  of  Nitrogen-fixing  organisms, 
to  provide  the  bacteria  with  improved  conditions 
which  favour  their  rapid  growth  and  development, 
to  supply  both  them  and  the  plants  with  an  ideal 
organic  food  that  they  can  readily  absorb,  directly 
or  indirectly,  to  furnish  an  increased  supply  of 
auximones,  and  in  a  very  marked  extent  to  improve 
the  texture  of  the  soil.  When,  therefore,  the  state- 
ment is  made  that  humogen  is  a  substance  suitable 
for  all  plants  and  for  all  soils,  it  is  a  statement  com- 
parable with  such  a  one  as  that  Carbon  dioxide  and  air 
and  water  are  necessary  for  all  plants  and  for  all  soils. 

In  this  respect  a  comparison  with  water  may 
make  the  matter  somewhat  clearer.  While  water  is 
essential  for  all  plant  growth,  its  addition  to  a 
water-logged  soil  would  only  be  productive  of  harm, 
a  condition  of  affairs  closely  analogous  with  what 
occurs  when  an  excess  of  artificial  or  natural  manure 
is  added  to  a  soil  that  is  already  rich  in  the 
material  supplied.  The  analogy,  so  far  as  the  peat 
is  concerned,  is  in  no  way  comparable,  for  if  humogen 
is  added  to  a  soil  already  rich  in  foods  the  bacteria 
grow  luxuriantly,  they  increase  in  numbers,  and 
enable  the  plant  to  use  to  advantage  the  foods 
already  present. 

In  order  to  obtain  the  best  results  from  the  use  of 


HOW  HUMOGEN  IS  APPLIED  171 

humogen  two  facts  have  to  be  borne  in  mind.  The 
soil  must,  as  in  cultivation  generally,  be  open  to  the 
air,  and  its  neutral  or  alkaline  condition  must  be 
insured  by  the  presence  of  a  sufficiency  of  lime.  As 
regards  the  soil  texture  it  is  unnecessary  to  write  here, 
because  every  farmer  and  every  gardener  is  fully 
aware  of  the  importance  of  having  an  adequate  air- 
supply  for  the  roots  of  plants,  and  recognise  why  the 
ordinary  methods  of  good  cultivation  have  to  be 
employed.  Experience  in  the  past  with  nitrobac- 
terine  and  with  other  fertilizers,  however,  has  shown 
that  the  necessity  of  the  ground  being  adequately 
limed  has  often  not  been  sufficiently  recognized. 

No  soil,  it  has  been  proved  abundantly,  can  be 
fertile  unless  it  is  free  from  acidity.  In  many 
instances  the  neutral  or  alkaline  condition  of  the  soil 
is  obtained  by  general  good  cultivation  and  adequate 
aeration  of  the  soil  (see  Chapter  IX.,  on  the 
chemistry  of  the  soil).  If  the  land  after  this  treat- 
ment remains  acid,  acidity  can  be  removed  by 
dressing  with  quicklime  to  the  extent  of  about  £  ton 
to  the  acre,  or  by  dressing  with  air-slacked  lime 
to  the  extent  of  about  a  ton  to  the  acre.  The 
general  practice  should  be  to  apply  the  lime  in  the 
late  winter,  or,  with  heavy  clay  soils,  in  the  late 
autumn  or  early  winter.  Lime  is  an  essential  soil 
constituent,  because  it  is  a  plant  food,  because  it 
renders  the  potash  and  phosphates  in  the  soil 
available  to  the  plants,  because  it  insures  the  alkaline 
conditions  necessary  for  bacterial  activity,  and 
because  of  the  mechanical  effect  it  produces  on  soils 
generally  and  especially  on  clays. 


172  THE  SPIRIT  OF  THE  SOIL 

Fortunately  it  is  a  simple  matter  for  the  farmer, 
even  if  he  is  no  chemist,  to  determine  for  himself  by 
a  simple  test  whether  or  not  the  land  is  sufficiently 
limed.  To  find  out  whether  there  is  a  sufficiency  of 
lime  or  not  in  a  field,  handfuls  of  soil  should  be  taken 
haphazard  from  all  parts  of  the  field.  These  should 
be  well  mixed  together,  and  a  wineglassful  of  the 
mixture  should  be  poured  into  a  tumbler,  and  the 
tumbler  three  parts  filled  with  water.  A  teaspoon- 
ful  of  spirits  of  salts  (Hydrochloric  acid)  should  be 
poured  into  the  water,  and  if  a  sufficiency  of  lime  is 
present  bubbles  will  be  liberated  in  the  same  sort 
of  way  that  occurs  when  soda-water  is  poured  out 
from  a  soda-water  syphon.  If  the  water  does  not 
bubble  freely,  there  is  a  deficiency  of  lime  in  the 
soil,  and  this  must  be  made  good  before  either 
humogen  can  be  usefully  applied,  or  the  land  yield 
a  satisfactory  crop.  In  some  soils  not  greatly 
deficient  in  lime  basic  slag  may  be  used  as  a 
substitute. 

When  humogen  is  required  for  field  work  on  the 
principles  of  intensive  culture  that  obtain  in  market 
gardens  as  contrasted  with  farm  work,  it  should 
be  used  in  the  proportion  of  10  cwt.  to  the  acre. 
It  should  be  spread  over  the  ground,  and  then 
ploughed  or  dug  in  so  as  to  be  well  mixed  with 
the  soil,  and  to  lie  some  3  to  6  inches  below  the  level 
of  the  ground.  So  far  as  possible  it  should  be  applied 
a  fortnight  or  three  weeks  before  using  the  ground. 
That  single  application  should  be  all  the  treatment 
required  in  the  course  of  the  year.  In  the  event  of 
it  not  being  possible  to  put  on  the  humogen  at  the 


HOW  HUMOGEN  IS  APPLIED  173 

time  of  digging,  the  same  quantity  may  be  top- 
dressed  and  harrowed  in  at  a  later  date  when  the 
plants  are  in  the  soil.  In  that  case  the  results  would 
be  less  certain  for  many  reasons,  an  important  one 
being  that  the  comparative  dryness  of  the  soil  may 
interfere  with  the  proper  growth  of  the  bacteria. 
In  any  case  it  should  be  borne  in  mind  that  it  is 
essential  that  the  humogen  should  be  got  well  into 
the  ground.  Another  practical  point  of  great  im- 
portance is  that  the  humogen  and  the  lime  must  not 
be  applied  together.  After  lime  has  been  applied,  at 
least  six  weeks  must  elapse  before  the  application  of 
the  humogen,  and  the  longer  the  intervening  period 
the  better.  Failing  that,  the  soluble  humates  in  the 
humogen  may  be  changed  into  insoluble  Calcium 
humate,  which  is  not  immediately  available  as  a 
plant  or  bacterial  food,  and  there  is  a  considerable 
waste  of  nitrogenous  food  liberated  in  the  form  of 
Ammonia. 

The  method  of  application  described  above  is  that 
recommended  generally  for  kitchen  gardens,  market 
gardens,  and  orchards. 

When  it  is  desired  to  apply  humogen  to  herbaceous 
flower  borders,  to  roses  or  sweet  peas,  the  humogen 
should  be  worked  into  the  soil  as  described  above 
either  in  February  or  March.  Eight  or  twelve  ounces 
should  be  applied  to  the  square  yard,  because  such 
gross  feeders  will  repay  for  the  extra  manuring  and 
throw  a  constant  succession  of  blooms.  Fruit 
borders,  with  espaliers,  cordons,  vines,  peaches, 
nectarines,  strawberries,  etc.,  require  the  same 
treatment  as  the  above;  but  if  the  plants  are  being 


I74  THE  SPIRIT  OF  THE  SOIL 

grown  under  glass,  the  ground  should  be  watered 
well  after  application. 

In  the  case  of  pot  plants  generally,  including 
cucumbers,  melons,  and  marrows,  the  compost 
suitable  for  the  requirements  of  the  plants  should  be 
used,  omitting  leaf  mould.  The  best  results  so  far 
have  been  obtained  by  using  i  part  of  humogen  to 
9  parts  of  compost. 

For  grass,  lawns,  golf-greens,  and  tennis-courts, 
humogen  should  be  applied  in  February  as  a 
top  -  dressing,  at  the  rate  of  4  ounces  to  the 
square  yard,  or  approximately  10  cwt.  to  the 
acre. 

A  valuable  liquid  stimulant  can  be  obtained  by 
soaking  a  pint  of  humogen  in  2  gallons  of  warm 
water,  allowing  it  to  stand  overnight,  and  using  the 
liquid  undiluted  when  watering.  Such  a  liquid  has 
all  the  advantages  of  a  Nitrogen  stimulant  without 
the  drawbacks.  In  applying  the  liquid  extract  of 
humogen  the  grower  is  enriching  the  soil  with 
bacteria,  which  will  continue  yielding  available 
Nitrogen  and  auximones.  By  this  means  the  plant 
is  developed  completely,  and  there  is  not  simply  a 
stimulation  of  leaf  development  as  occurs  with 
nitrate  stimulants.  There  is  very  seldom  any  danger 
of  the  plant  being  injured  by  even  extreme  strength 
of  the  liquid.  It  can  be  given  as  dark  coloured  as 
black  coffee,  and  in  that  concentration  it  is/most 
effective  if  a  powerful  stimulant  is  required.  As  is 
the  case  when  the  humogen  is  applied  in  other 
forms,  free  and  perfectly  balanced  growth  is  pro. 
moted. 


HOW  HUMOGEN  IS  APPLIED  175 

Good  results  can  be  obtained  by  using  humogen 
with  other  fertilizers,  particularly  if  they  are  not 
acid  in  character,  as  is  the  case  with  many  artificial 
manures  and  fresh  dung.  Old  rotted  stable  manure, 
when  mixed  with  a  twentieth  part  of  its  bulk  of 
humogen,  is  a  valuable  fertilizer,  easily  applied,  and 
combines  the  good  qualities  of  both  dung  and 
humogen.  There  is  no  reason,  however,  why 
humogen  should  not  be  used  alone  without  any  other 
fertilizer,  and  so  far  experiments  have  demonstrated 
that  alone  it  will  do  all  that  dung  and  artificial 
manure,  either  separately  or  together,  are  able  to 
effect.  A  basis  of  dung  or  other  bulky  organic 
manure  has  distinctly  beneficial  effects  on  the 
mechanical  texture  of  the  soil  apart  from  any 
manurial  value  that  it  may  have.  Its  presence  is 
definitely  advantageous  in  extreme  soils — that  is, 
heavy  clays  or  light  sands — and  well  worth  con- 
sideration. 

It  should  be  noted  carefully  that  when  humogen  is 
applied  to  bulbs  and  corms  only  i  part  of  humogen 
to  20  parts  of  soil  should  be  used.  In  all  experi- 
ments carried  out  with  monocotyledons  it  has  been 
found  that  one-half  of  the  dressing  required  for 
ordinary  plants  is  sufficient. 

In  considering  the  application  of  humogen  to 
agricultural  conditions  it  is  not  possible  to  speak  as 
yet  with  the  same  degree  of  certainty  as  it  is  in 
horticultural  and  glass  work.  The  present  year, 
for  instance,  with  its  seven  weeks  of  continuous 
drought,  has  resulted  in  many  field  experiments 
giving,  so  far  as  can  be  seen  at  present,  nega- 


176  THE  SPIRIT  OF  THE  SOIL 

live  results.  It  had  been  hoped  that  the  infor- 
mation gained  this  year  would  have  made  it 
possible  to  lay  down  definite  rules  as  to  quantities 
advisable  in  varying  conditions,  and  so  forth.  At 
present,  unfortunately,  one  has  still  to  be  guided  by 
the  experience  gained  in  the  market  gardens.  A  diffi- 
culty, however,  that  will  occur  to  every  practical 
farmer  can  at  once  be  stated  and  met.  Inevitably  a 
large  quantity  of  farmyard  manure  will  be  produced 
year  by  year  under  present  farming  conditions,  and 
the  supply  will  perhaps  reach  the  half  of  all  the 
manure  required  on  the  farm.  The  question  natur- 
ally arises  as  to  what  is  to  be  done  with  this  manure 
if  humogen  is  used.  Probably  the  best  solution 
would  be  to  spread  this  over  the  whole  farm,  and  to 
supplement  it  with  humogen.  In  this  way  the  level 
of  the  fertility  of  the  soil  would  be  raised  to  a  higher 
standard  than  has  obtained  in  the  past.  Five  hun- 
dredweights of  humogen  to  the  acre  applied  in  the 
spring,  top-dressed  and  harrowed  in,  should  greatly 
increase  the  yield  of  the  farms  if  the  results  obtained 
in  small  plot  experiments  hold  good  when  the  treat- 
ment is  transferred  to  the  farm.  Up  to  the  present 
the  results  are  indefinite,  and  do  not  bear  tabulation. 
The  results  given  in  the  appendices,  with  rare  excep- 
tions, are  of  a  market  garden  or  greenhouse  order, 
but  it  is  hoped  in  later  editions  of  this  book  that  it 
will  be  possible  to  give  definite  statements  as  to  the 
amounts  of  material  used  and  so  forth.  Generally 
one  may  advise  the  application  of  from  5  to 
10  cwt.  to  the  acre  for  roots  generally,  potatoes 
especially  responding  well  to  the  larger  amount. 


HOW  HUMOGEN  IS  APPLIED  177 

Experiments  now  in  progress  seem  to  justify  the 
anticipation  that  the  crops  will  be  greatly  increased. 
It  is  perhaps  worth  noting  again  here  that  under 
experimental  conditions  wheat  and  other  cereals 
have  responded  well  to  humogen  treatment,  showing 
improved  tillering,  larger  ears,  and  increased  growth 
of  the  straw. 


V 


CHAPTER  XIV 

GENERAL    RESULTS 

Experimental  character  of  horticulture  and  agriculture — 
Benefits  from  inoculation — Selection  of  results — Difficulties 
of  exact  measurements — Need  for  farm  experiments — 
Three  arguments  justifying  them — Experiments  on  apples. 
Asparagus.  Asters.  Auricula.  Balsam,  Barley.  Beans. 
Beetroot.  Begonia.  Broccoli.  Brussel  sprouts.  Cabbages. 
Calla.  Carnations.  Carrots.  Cauliflowers.  Celery.  Chrys- 
anthemums. Clover.  Coleus.  Cordyline.  Cotton.  Crassula. 
Cress.  Crocuses.  Crotons.  Cucumbers.  Cyperus. 
Daffodil.  Dahlias.  Daisies.  Ferns.  Fuchsia.  Geranium. 
Gloxinia.  Grass.  Grevillea.  Hippeastrum.  Hyacinths. 
Iresine.  Iris.  Isoloma.  Jacobinia.  Lantana.  Leonitis. 
Lettuces.  Lilium.  Maize.  Marrows.  Mustard.  Nas- 
turtium. Nerium.  Nicotiana.  Onions.  Orchids.  Parsnips. 
Peas.  Potatoes.  Primula.  Pyrethrum.  Radishes.  Rhu- 
barb. Roses.  Schizanthus.  Scutellaria.  Streptocarpus. 
Sweet  peas.  Tomatoes.  Turnips.  Wallflowers.  Wheat. 

THE  contention  of  the  present  volume  is  that  soil 
inoculation  scientifically  carried  out  will  greatly 
increase  the  yield  of  the  land  that  is  already  under 
cultivation,  that  it  will  bring  into  cultivation  large 
tracts  of  land  that  it  has  hitherto  not  paid  to  culti- 
vate, and  that  by  the  stimulation  of  plants  it  will  be 
possible  to  bring  fruit  and  flowers  to  maturity  earlier 
than  can  be  done  by  other  means.  In  the  present 
chapter  I  propose  briefly  to  indicate  the  results  that 
experience  has  shown  can  be  achieved  by  the  grower. 

178 


GENERAL  RESULTS  179 

I  am  not  pretending  that  such  results  will  always 
follow  on  the  application  of  bacterized  peat.  How- 
ever careful  the  directions  given,  it  is  inevitable  that 
from  time  to  time  mistakes  will  be  made  in  the 
methods  used  for  employing  the  peat,  and  the  com- 
plexity of  Nature  is  such  that  special  conditions 
will  inevitably  arise  where  results  will  fall  short  of 
anticipation.  The  practical  grower  and  the  amateur 
gardener  hardly  need  to  be  told  that  both  horti- 
culture and  agriculture  are  still,  despite  centuries 
of  accumulated  experience,  to  a  large  extent  in  the 
experimental  stage,  and  it  would  be  unreasonable 
to  expect  that  after  ten  years  of  experimental  work, 
much  of  it  perforce  done  in  the  laboratory  and  the 
hothouse,  there  can  be  the  same  degree  of  certainty 
which  may  fairly  be  expected  from  methods  which 
have  stood  the  test  of  centuries. 

It  has  not  been  an  easy  matter  to  select  typical 
results  from  the  evidence  available.  Experiments 
have  been  tried  with  success  on  many  species  other 
than  those  of  which  mention  is  made,  but  I  have 
attempted  to  select  those  species  which  are  more 
commonly  under  cultivation.  At  the  outset  I  would 
state  frankly  that  the  presentation  of  the  results  is 
faulty.  Scientific  methods  would  require  the  state- 
ment of  exact  comparative  weights  and  measure- 
ments with  standardized  tests  of  colour,  and  so  forth. 
The  conditions  under  which  such  work  can  be  done, 
however,  cannot  readily  be  complied  with.  The 
horticulturist  and  the  farmer  who  in  the  past  years 
have  been  willing  to  give  a  trial  to  bacterized  peat 
are  inevitably  men  who  have  other  business  to 


i8o  THE  SPIRIT  OF  THE  SOIL 

attend  to  beside  that  of  undertaking  the  extremely 
difficult  work  of  accurate  measurement.  To  have 
carried  such  work  out  on  a  satisfactory  scale  from 
the  standpoint  of  exact  science  would  have  required 
a  large  number  of  highly  trained  workers,  and  even 
had  that  policy  been  pursued  there  would  have  been 
people  to  raise  the  objection  that  the  results  were 
results  obtained  by  the  laboratory  man,  and  not 
by  the  practical  worker.  Several  cases  where  exact 
measurements  have  been  taken  will  be  found  re- 
corded in  Appendix  B,  and  as  regards  the  results 
which  follow  here  the  statement  may  be  made  that 
authority  can  be  given  for  each  generalization  made. 
In  some  cases  the  deductions  are  based  on  a  single 
experiment,  but  in  most  instances  the  claims  put 
forward  can  be  endorsed  by  evidence  obtained  from 
several  growers. 

A  characteristic  of  supreme  importance  from  the 
material  standpoint  will  be  noted.  The  majority  of 
the  results  refer  to  experiments  carried  out  by  horti- 
culturists rather  than  farmers.  So  far  bacterized 
peat  has  been  tested  chiefly  by  the  horticulturist, 
the  man  who  stands  midway  between  the  experi- 
mental botanist  and  the  farmer.  The  value  of  soil 
inoculation  effected  by  means  of  bacterized  peat 
has  been  proved  conclusively  in  the  laboratory. 
The  experiments  conducted  at  Kew  Gardens  and 
those  carried  out  by  horticulturists  and  market 
gardeners,  both  under  glass  and  in  the  open,  have 
endorsed  the  laboratory  experience.  Such  experi- 
ments as  have  been  made  under  farming  conditions 
indicate  that  there  is  every  reason  to  believe  that 


GENERAL  RESULTS  181 

the  results  obtained  in  the  laboratory  and  the  field 
are  also  available  to  the  farmer,  and  the  main  object 
of  the  present  book  will  have  been  attained  if  it 
induces  those  who  alone  are  in  a  position  to  carry 
out  these  experiments  on  a  grand  scale  to  extend  the 
scope  of  our  present  experience.  Three  arguments 
should  serve  to  convince  them :  The  first,  that  the 
experiments  have  proved  successful  both  in  the 
laboratory  and  market  garden ;  the  second,  that  the 
American  Board  of  Agriculture  are  encouraging  the 
farmers  in  America  to  make  use  of  inoculation  even 
on  lines  only  slightly  modified  from  those  which  a 
few  years  ago  were  partially  successful  in  this 
country ;  and  the  third,  that  the  use  of  the  bacterized 
peat,  even  if  it  were  not  to  benefit  the  crop,  is 
incapable  of  doing  it  harm. 

For  purposes  of  convenience  I  have  thought  it 
simplest  to  describe  the  experiments  in  alphabetical 
order,  and  to  save  space  I  have  compressed  the 
results  into  the  smallest  possible  compass.  It  should 
be  borne  in  mind  that  the  nature  of  the  treated  peat 
is  such  as  to  make  it  valuable  in  the  case  of  all  plants. 

Except  where  otherwise  stated,  control  plants 
have  received  the  manure  or  fertilizers  commonly 
accepted  as  suitable  for  them,  while  often  the  best 
known  treatment  has  been  given. 

APPLES. — Increased  vigour  of  growth  followed 
treatment.  The  wood  was  stronger  and  riper.  The 
foliage  was  a  rich  dark  green.  There  was  an  average 
gain  of  i£  ounces  on  each  fruit,  and  the  fruit  ripened 
about  a  fortnight  earlier  than  on  untreated  trees. 
In  the  second  year  there  was  no  further  application 


182  THE  SPIRIT  OF  THE  SOIL 

of  the  treated  peat,  but  the  trees  showed  a  robust 
health,  and  were  more  heavily  laden  than  usual  with 
fruit.  The  experiments  were  tried  with  the  Blen- 
heim Orange  and  Cox's  Orange  Pippin. 

ASPARAGUS. — The  tests  were  made  with  aspara- 
gus seedlings.  At  the  end  of  the  season  the  growth 
was  such  that  the  plants  were  a  year  nearer  bearing 
than  those  which  had  not  been  treated,  to  judge 
by  the  increased  size  of  the  roots.  The  foliage 
of  the  treated  plants  was  of  better  colour  and 
substance. 

ASTERS. — The  seeds  sown  in  the  soil  treated  with 
bacterized  peat  gained  from  the  seed-leaf  stage  until 
the  time  of  flowering,  when  the  plants  were  more 
than  double  the  size  of  those  which  had  not  been 
dressed  with  the  peat.  They  formed  bouquets  of 
flowers  averaging  5  inches  across  (Comet  Aster),  as 
against  4  inches  in  plants  not  treated.  The  foliage 
and  the  stems  were  both  stronger  and  larger. 

AURICULA. — Increase  in  growth  followed  treat- 
ment, and  the  plants  treated  were  quite  free  from 
woolly  aphis,  while  those  which  had  not  been  treated, 
though  in  the  same  house,  were  attacked. 

BALSAM  IMPATIENS. — The  results  obtained  with 
Balsam  were  very  striking.  One  object  of  the 
experiment  was  to  determine  how  far  the  plant, 
notoriously  liable  to  eel-worm,  would  be  rendered 
immune.  Experience  showed  that  there  were  no 
signs  of  eel-worm  among  the  treated  plants,  whereas 
those  not  treated  succumbed  to  the  disease. 

BARLEY.  —  Laboratory  experiments  conducted 
with  barley  were  very  promising.  There  was  a  deep 


FIG.    14 

French  runner  beans  as  grown  in  Guernsey.  The  plant  on  the  right 
was  treated  with  humogen  and  yielded  more  beans  than  the  plant 
on  the  left.  The  total  increase  of  the  two  such  treated  plants  over 
the  two  such  untreated  plants  was  S6'5  per  cent. 

(Grown  by  Mr.  Holmes,  Tuckswood  Farm,  Norwich.) 


GENERAL  RESULTS  183 

green  colouring  to  the  leaves,  and  the  culms  were 
much  stronger.  The  tillering  was  better. 

BEANS,  RUNNER. — The  treated  plants  were  earlier 
above  ground  than  those  not  treated.  Their  growth 
was  more  rapid,  and  they  attained  a  greater  height 
and  developed  enormous  healthy  green  leaves,  in 
some  cases  as  large  as  dinner-plates.  In  some 
instances  the  pods  were  as  much  as  15  inches  long, 
while  they  averaged  about  12  inches.  They  retained 
their  vigour  when  the  untreated  plants  yellowed 
off,  and  the  yield  was  increased  by  20  per  cent,  or 
more. 

BEETROOT. — This  root  responds  quite  exception- 
ally well  to  humogen  treatment.  A  gain  of  50  per 
cent,  over  other  fertilizers  has  been  the  rule  rather 
than  the  exception,  this  gain  being  maintained  with 
turnip  and  long  beet,  and  also  with  the  sugar  beet. 
The  quality  of  the  beet  has  been  found  to  be  greatly 
improved.  The  roots,  although  very  much  larger, 
were  excellent  in  colour  and  flavour,  woolliness  being 
conspicuous  by  its  absence. 

BEGONIA. — The  peat-treated  plants  were  more 
robust  and  heavier  flowered  than  those  receiving 
soot  or  guano. 

BROCCOLI. — The  main  difference  between  the 
broccoli  and  the  cauliflower  is  the  superior  power  of 
resistance  of  the  former  vegetable  to  cold.  Both 
respond  admirably  to  treatment  with  peat  (see  under 
Cauliflower),  and  the  results  obtained  with  broccoli 
were  closely  comparable  with  those  got  on  cauli- 
flower. The  fact  is  especially  interesting  as  showing 
that  the  effect  of  the  treatment  is  to  stimulate  the 


i84  THE  SPIRIT  OF  THE  SOIL 

plant  into  active  growth  without  producing  a  soft, 
sappy  plant  that  would  succumb  to  frost.  The 
effect  was  to  make  the  plants  resistant,  sturdy,  and 
vigorous. 

BRUSSEL  SPROUTS. — In  this  instance  the  effect  of 
testing  peat  against  both  artificial  manures  and  dung 
was  to  give  an  increased  yield  of  better  quality. 
The  buttons  were  hard,  firm,  and  closely  set,  giving 
a  much  greater  average  yield  per  plant.  The  plants 
themselves  grew  taller,  and  the  flavour  was  dis- 
tinctly improved. 

CABBAGES. — Growth  was  earlier  and  sturdier. 
The  plants  showed  a  rich  bluey  green,  denoting 
perfect  health.  The  hearts  were  larger,  harder,  and 
crisper  than  in  untreated  plants.  They  were  ready 
for  market  earlier. 

CALLA. — In  calla  the  effect  was  very  noticeable. 
There  was  great  profusion  of  bloom,  and  the  root 
action  was  excellent.  The  foliage  was  a  rich  deep 
green,  and  the  blooms  were  splendid.  A  top-dressing 
of  i  ounce  of  humogen  on  a  10-inch  pot  full  of  food 
more  than  doubled  the  growth  in  a  month. 

CARNATIONS. — One  carnation  specialist  has  had 
plants  13!  inches  high  in  thumbs.  They  were  then 
still  growing,  and  were  the  equal  of  plants  which  had 
been  grown  in  3-inch  pots,  but  without  the  peat. 
Tested  against  various  carnation  specialities,  the 
peat-treated  plants  gave  much  more  satisfactory 
growth.  They  broke  freely  and  flowered  abun- 
dantly. The  plants  grown  in  the  humogen  resisted 
eel-worm,  while  those  without  it  succumbed.  One 
of  the  principal  prizes  at  Chelsea  and  Holland  House 


GENERAL  RESULTS  185 

this  year  (1915)  was  awarded  to  carnations  grown 
with  humogen. 

CARROTS. — The  yield  from  ground  treated  with 
peat,  as  compared  with  dung,  showed  an  increase  of 
28  per  cent.,  and  of  20  per  cent,  as  compared  with 
artificial  manures.  The  roots  were  clean,  straight, 
and  of  good  colour.  The  tops  were  not  so  big  as 
might  have  been  expected,  considering  the  size  of 
the  roots,  a  point  that  should  be  borne  in  mind  by 
users  of  treated  peat  who  wish  to  estimate  the 
progress  of  plants  under  treatment  from  week  to 
week.  The  remark  applies  generally  to  all  root 
crops,  including  potatoes. 

CAULIFLOWERS. — There  was  a  10  per  cent,  im- 
provement shown  by  plants  treated  over  plants  not 
treated.  The  heads  formed  earlier,  were  closer,  and 
generally  more  satisfactory. 

CELERY. — The  sticks  of  treated  celery  were  20  per 
cent,  larger  than  those  untreated,  and  were  hard  and 
nutty.  They  were  pulled  three  weeks  earlier,  and 
the  crop  was  altogether  much  heavier.  The  colour 
of  the  plants  was  a  rich,  dark,  glaucous  green,  and 
the  stems  were  free  from  frothiness.  Owing  to  the 
increased  vigour  and  hardier  nature  of  the  plants, 
they  were  much  less  affected  than  the  untreated 
plants  by  early  frosts. 

CHRYSANTHEMUMS. — The  leaves  of  the  treated 
plants  were  large,  well  formed,  thick,  and  of  a  dark 
green  colour,  while  the  foliage  was  retained  from 
the  base  upwards  throughout  the  season.  Growth 
was  free,  abundant,  and  sturdy,  and  there  was  a 
maximum  number  of  side-breaks.  In  the  blooms  a 


i86  THE  SPIRIT  OF  THE  SOIL 

striking  feature  was  the  improved  colour  and  sub- 
stance of  the  petals,  while  the  flowers  of  treated 
plants  retained  their  freshness  and  beauty  a  fortnight 
longer. 

CLOVER. — Clover  is  stimulated  in  a  very  marked 
manner,  the  plant  spreading  and  increasing  in  size 
rapidly.  It  very  soon  acquires  sufficient  strength 
to  displace  its  neighbours. 

COLEUS  in  variety.  A  striking  feature  apart  from 
the  increased  growth  was  the  extraordinary  intensity 
of  the  colours  in  the  foliage.  It  has  always  been  held 
generally  that  while  an  abundance  of  stimulating 
food  produces  growth,  it  sacrifices  variegation  and 
colour.  With  bacterized  peat  both  increase  in  size, 
and  very  vivid  colouring  were  obtained.  Similar 
results  were  obtained  with  abutylon.  (Photo,  p.  143.) 

CORDYLINE  DRACENA. — The  effect  of  humogen  on 
small  plants  of  this  species  was  to  produce  a  plant 
fit  for  the  market  in  two  months,  whereas  under 
ordinary  treatment  six  months  would  be  the  usual 
time  necessary.  In  the  experiments  made  the  root 
action  was  particularly  vigorous. 

COTTON. — The  plants  grew  taller,  and  they  were 
very  markedly  thicker  and  stronger  stemmed.  The 
leaves  were  larger,  and  the  plants  generally  had 
every  appearance  of  being  stronger  and  healthier. 
The  root  formation  in  the  pots  was  very  notice- 
able. 

CRASSULA  COCCINEA. — As  with  other  potted 
plants,  the  points  particularly  noticeable  were  the 
perfectly  balanced  growth,  the  profusion  of  bloom, 
and  the  increased  root  action.  Foliage  responded 


GENERAL  RESULTS  187 

well  to  the  treatment,  and  the  colour  of  the  blooms 
was  intensified. 

CRESS. — The  effect  of  the  treated  peat  on  cress  is 
excellent,  and  this  plant  is  admirably  adapted  for 
showing  the  effect  of  peat  experimentally  on  a  small 
scale.  In  the  opinion  of  one  grower  the  improve- 
ment in  size,  flavour,  and  substance  was  such  as  to 
justify  100  per  cent,  increase  in  the  price  charged- 
To  repeat  the  experiment  it  is  only  necessary  to  sow 
cress  seeds  in  a  shallow  box  containing  ordinary 
garden  soil,  and  to  compare  this  with  a  box  under 
similar  conditions  with  treated  peat  added  in  the 
proportion  of  i  :  12.  Germination  may  be  slightly 
delayed,  but  the  ultimate  effect  is  assured.  The 
second  cutting  of  the  treated  cress  has  in  many  cases 
been  heavier  than  the  first  cutting  of  the  untreated 
cress. 

CROCUSES. — Foliage  and  flowers  were  greatly  im- 
proved. The  resulting  corms  were  bigger  and 
heavier,  giving  promise  of  better  results  in  the  fol- 
lowing year. 

CROTONS. — The  plants  were  much  finer,  and  the 
colour  in  the  foliage  was  greatly  intensified.  Root 
action  was  very  strong.  (Photo,  p.  159.) 

CUCUMBERS. — Twenty  days  after  planting  the 
cucumbers  which  had  been  peat-treated,  cutting 
commenced,  72  cucumbers,  weighing  73  pounds, 
being  cut  from  18  plants  before  the  untreated  plants 
yielded  a  fruit  (June  7).  A  fortnight  later  119 
cucumbers,  weighing  119  pounds,  had  been  cut 
from  the  treated,  as  against  58  cucumbers,  weighing 
51  pounds,  from  an  equal  number  of  untreated 


i88  THE  SPIRIT  OF  THE  SOIL 


plants.  The  fruits  were  heavier;  the  foliage  was 
slightly  smaller,  but  of  a  much  deeper  green.  The 
root  action  was  very  vigorous,  top-dressings  being  re- 
quired much  more  often  than  for  the  untreated  plants. 

CYPERUS  VEGETUS. — There  was  three  times  as 
much  growth  and  bloom.  The  treated  plants  were 
still  in  full  vigour  when  the  control  plants,  in  a  com- 
plete soil  mixture,  were  showing  signs  of  starvation. 

DAFFODIL. — Stronger  growth  was  observed,  and 
there  were  45  per  cent,  more  blooms  from  the  same 
number  of  bulbs.  The  flowers  stood  well  above  the 
foliage. 

DAHLIAS. — -The  effect  on  the  growth  of  dahlias  was 
very  striking.  Although  growth  was  so  strong  the 
flowers  were  thrown  well  away  from  the  foliage. 
The  colours  of  the  blooms  had  a  glowing  richness, 
and  in  their  number  and  quality  fully  corresponded 
with  the  growth. 

DAISIES  (Chrysanthemum  Max). — The  flowers  were 
larger,  earlier,  and  better,  and  cutting  commenced 
a  fortnight  earlier. 

FERNS  (Adiantum,  Pteris,  Asparagus  Plumosa 
and  Sprengeri). — Ferns  respond  very  quickly  to 
treatment,  and  produce  good  saleable  plants  in  a 
third  of  the  time  usually  taken.  Experiments  con- 
firming this  result — as  in  many  of  the  other  cases 
here  quoted — have  been  in  progress  for  three  years. 

FUCHSIA. — The  usual  characteristics  of  the  effect 
of  humogen  on  pot  plants  have  been  well  marked  in 
the  case  of  the  fuchsia — the  well-balanced  sym- 
metrical growth,  profusion  of  bloom,  energetic  root 
action,  rich  foliage,  and  intensification  of  the  colour 


GENERAL  RESULTS  189 

of  the  bloom.  The  pyramidal  formation  of  the 
plants  has  been  very  noticeable.  In  one  typical 
series  of  experiments  the  plants  bloomed  six  weeks 
after  potting  at  the  end  of  May,  and  continued  in 
flower  until  October. 

GERANIUM. — Several  tests  have  been  made  with 
geraniums,  and  it  has  repeatedly  been  found  that 
the  treated  plants  continued  growing  and  blooming 
when  plants  without  the  peat  were  starved.  One 
grower  has  reported  that  he  has  by  means  of  the 
peat  been  able  to  obtain  geraniums  by  May  or  June, 
selling  them  at  45.  a  dozen,  whereas  under  former 
conditions  he  used  to  obtain  only  2s.  6d.  a  dozen. 

GLOXINIA. — These  made  excellent  glossy  foliage, 
and  flowered  profusely.  The  plants  generally  were 
better  and  bigger  in  every  way. 

GRASS. — In  connection  with  golf-greens,  cricket- 
pitches,  and  lawns,  humogen  has  been  tried  against 
a  mixture  of  malt  culms,  soot,  and  ammonium  sul- 
phate, and  in  every  way  the  peat  has  proved  superior. 
The  grass  becomes  a  beautiful  dark  green,  the  clover 
in  it  is  thickened,  and  a  much  better  bottom  is  devel- 
oped. A  well-known  golf  professional  has  described 
how  a  week  after  the  application  of  the  peat  the 
portions  of  greens  treated  could  easily  be  distin- 
guished from  a  long  distance  off. 

GREVILLEA  ROBUSTA. — After  treatment  the  plants 
grew  so  rapidly  that  they  became  too  big  for  the 
greenhouse.  A  notable  feature  was  the  way  in 
which  the  plant  branched,  breaks  occurring  at  al 
axils,  and  resulting  in  a  dense  mass  of  foliage. 
(Photo,  Frontispiece.) 


I9o  THE  SPIRIT  OF  THE  SOIL 

HIPPEASTRUM. — Seedlings  by  the  end  of  the 
season  had  made  bulbs  two  and  a  half  times  as  heavy 
as  in  the  case  of  untreated  plants.  They  were 
therefore  so  much  the  nearer  by  that  extent  to  the 
flowering  stage. 

HYACINTHS. — Increase  in  the  root  action  was  well 
marked.  The  foliage  was  rich  in  colour.  The  flower 
spikes  were  heavier,  and  both  colour  and  scent  were 
strongly  intensified.  The  bulbs  were  heavier. 
(Photo,  p.  91.) 

IRESINE  LINDENI. — The  purplish  red  attained  in 
the  foliage  was  very  striking.  The  growth  obtained 
was  less  remarkable,  but  the  colouring  was  far  more 
intense,  deeper,  and  richer. 

IRIS  HISPANICA. — Growth  was  more  vigorous ;  the 
flowers  were  bigger,  and  matured  a  week  earlier. 

ISOLOMA. — Fine  healthy  plants  were  obtained  far 
larger  than  in  the  case  of  non-treated  plants.  Those 
receiving  humogen  showed  greatly  increased  root 
action,  much  improved  foliage,  intensification  of 
flower  coloration,  and  a  notable  symmetrical 
development. 

JACOBINIA. — Results  were  obtained  similar  to 
those  in  the  case  of  isoloma,  but  owing  to  the  intensi- 
fication of  colouring  the  blue  flowers  made  a  striking 
picture  against  the  dark  green  foliage. 

LANTANA  SABRIFOLIA. — The  rapidity  of  growth 
obtained  without  spoiling  balance  was  very  marked. 
The  plants  were  more  than  double  the  size  of  those 
not  treated. 

LEONITIS  LEONURUS. — Symmetry,  strongly  pro- 
moted root  action,  intensification  of  colour  of  foliage 


FIG.    15 

The  maize  plant  was  one  of  the  earliest  on  which  auximones  were 
tested.  All  the  plants  shown  above  were  grown  in  sterilized  sand 
(washed  silver  sand).  The  plant  on  the  right  received  nothing  but 
distilled  water.  The  middle  one  received  a  complete  chemical  diet 
(Detmer's).  The  one  on  the  left  received  Detmer's  +0*35  part  per 
million  of  the  Silver  fraction  derived  from  the  Phosphotungstic 
precipitates  obtained  from  bacterized  peat.  The  photograph  had 
to  be  taken  at  an  early  stage,  as  the  plant  grown  with  distilled  water 
was  beginning  to  die. 
(Botanical  Laboratories,  University  of  London,  King's  College.) 


GENERAL  RESULTS  191 

and  flower,  and  perfectly  balanced  growth,  with 
increase  in  size,  were  well  marked  in  the  treated 
plants. 

LETTUCES. — A  series  of  experiments  carried  out 
in  a  dry  spring  showed  a  superiority  of  the  peat  over 
dung  of  123  per  cent.,  and  of  the  peat  over  artificial 
manure  of  176  per  cent.  The  plants  were  markedly 
good-looking,  and  hearted  well. 

LILIUM  HARRISII. — In  addition  to  showing  the 
characteristics  usually  following  the  use  of  peat  with 
pot  plants  there  was  an  average  increase  of  8  inches 
in  height,  though  the  pots  were  smaller  than  those 
ordinarily  used.  The  number  of  blooms  per  plant 
was  usually  six  or  seven. 

MAIZE. — Remarkable  results  were  obtained  with 
experiments  conducted  in  sand  culture  with  maize  to 
testthe  effect  of  auximones.  The  weights  of  the  dried 
plants  under  different  treatment  were  as  follows: 

Grammes. 

Sterilized  sand  and  distilled  water  . .        66 

Sterilized  sand  and  Detmer's  solution     . .     215 
Sterilized   sand,    Detmer's    solution,    and 
phosphotungstic  fraction  from  humogen 
(17  parts  in  1,000,000)    . .  . .          . .     255 

Sterilized  sand,  Detmer's  solution,  and 
Silver  nitrate  fraction  from  bacterized 
peat  (0-35  part  in  1,000,000)  . .  . .  325 

MARROWS  (Bush). — When  marrows  were  treated 
with  artificial  manures  the  average  weight  of  the 
fruits  obtained  per  plant  was  16  pounds  5  ounces. 
When  treated  with  peat  the  fruits  weighed  37  pounds 
ii  ounces.  The  plants  fruited  a  week  earlier,  and 
continued  bearing  after  the  others. 

MUSTARD. — Peat  treatment  gave  an  increased 
yield  of  174  per  cent.  The  leaves  were  darker  all 


192  THE  SPIRIT^OF  THE  SOIL 

the  time  the  plants  were  growing  and  had  thicker 
stems,  the  effect  being  most  marked  when  the  crop 
was  ready  to  cut. 

NASTURTIUM. — When  peat  was  used  in  small 
quantities  the  plants  improved  in  every  respect,  but 
when  a  full  dressing  of  peat  was  used  the  plants 
became  too  vigorous,  developing  a  huge  foliage  that 
concealed  the  flowers. 

NERIUM  OLEANDER. — In  addition  to  increased 
root  and  foliage  development,  and  a  marked  increase 
in  the  size  of  the  plants,  the  flowers  themselves  were 
larger  and  more  numerous,  and  showed  a  striking 
increase  in  colour. 

NICOTIANA  (Tobacco  Plant). — The  plants  were 
stouter  stemmed,  broader  leaved,  and  taller. 

ONIONS. — In  one  experiment  treatment  with  the 
peat  was  followed  by  an  increase  of  41  per  cent.  In 
another  experiment,  when  no  manure  was  used  as  a 
control,  the  treated  plants  showed  an  increase  of 
no  per  cent.,  and  where  dung  was  used  as  a  control, 
of  46  per  cent.  The  plants  grown  in  soil  mixed  with 
humogen,  as  compared  with  those  that  had  received 
dung,  had  much  smaller  tops,  the  necks  were 
thinner,  and  the  bulbs  harder  and  bigger,  and 
they  proved  better  keepers. 

ORCHIDS  (Veitchii  Calanthe). — The  plants  pro- 
duced spikes  earlier  and  heavier  than  those  which 
had  not  received  peat. 

PARSNIPS. — Three  drills  were  dressed  with  humo- 
gen this  year  (1915),  and  grown  against  eight  drills 
undressed.  Those  treated  with  humogen  are  much 
more  forward  and  growing  more  evenly. 


GENERAL  RESULTS  193 

PEAS. — In  one  of  many  experiments  there  was  a 
31  per  cent,  gain  in  weight  of  the  pods  pulled  for 
eating.  The  plants  were  taller,  and  the  pods  were 
both  larger  and  more  numerous.  In  another  experi- 
ment on  peas  grown  for  seed  three  rows  untreated 
gave  18  pounds  of  dry  seed,  while  three  treated  rows 
gave  28  pounds  of  seed,  an  increase  in  weight  of 
55  per  cent.,  representing  to  the  grower  a  money 
gain  of  i8s.  3d. 

POTATOES. — Compared  with  no  manure,  artificial 
manures  and  dung,  peat  has  given  an  increase  in 
potatoes  over  no  manure  of  123  per  cent.,  over  arti- 
ficial manures  of  75  per  cent.,  and  over  dung  of 
41  per  cent.  These  results  were  obtained  in  a  light 
sandy  loam  in  1913,  the  land  not  having  been 
previously  cultivated  for  nine  years.  In  1914  the 
same  ground  treated  with  humogen  gave  an  increase 
of  59*5  per  cent,  over  land  not  manured.  A  part  of 
each  of  the  plots  manured  in  1913  was  left  un- 
manured  in  1914.  The  land  which  had  received  arti- 
ficial manures  showed  an  increase  of  27  per  cent, 
over  the  unmanured  land,  the  peat-treated  land 
showed  an  increase  of  83*3  per  cent.,  while  the  land 
that  had  received  dung  showed  an  increase  of  37*7 
per  cent.  The  treated  peat  appeared  to  leave  the 
land  as  fertile  the  second  year  as  in  the  season  of 
application. 

PRIMULA  (Malacoides,  Kewensis,  Obconica,  etc.}. — - 
All  varieties  of  primula  tested  responded  equally 
well,  the  plants  in  each  case  showing  100  per  cent, 
superiority.  The  flowers  were  more  prolific,  and 
individually  larger  and  better  coloured. 

13 


194  THE  SPIRIT  OF  THE  SOIL 

PYRETHRUM. — Cutting  was  ten  days  earlier.  Stems 
were  markedly  longer,  and  the  characteristic  feathery 
foliage  better  developed. 

RADISHES. — A  striking  result  has  been  obtained 
with  radishes  grown  in  soil  as  against  the  same  soil 
and  humogen.  Two  rows  were  grown  against  each 
other.  The  weight  of  the  best  twelve  plants  in  the 
humogen  row  was  6|  ounces ;  of  the  second  best  dozen 
5^  ounces.  Only  a  dozen  weighable  radishes  were 
obtained  from  the  untreated  row,  and  they  weighed 
only  3f  ounces.  (Photo,  p.  194.) 

RHUBARB. — Early  this  year  (1915)  a  very  small 
dressing  of  peat  was  given  to  a  portion  of  a  plot  of 
growing  rhubarb.  By  June  5  the  treated  portion 
was  very  much  better  than  the  untreated.  It  was 
ready  for  pulling  earlier,  and  growth  continued 
longer,  stalks  being  pulled  from  it  after  growth  had 
ceased  in  the  other  part  of  the  plot. 

ROSES. — Excellent  results  have  been  obtained 
with  roses.  The  plants  increased  in  vigour,  and  the 
healthiness  of  the  foliage  and  the  colour  of  the 
blooms  were  intensified.  So  well  marked  is  the  latter 
quality  that  two  beds  of  Dean  Hole,  one  of  which 
was  treated  and  the  other  untreated  with  the 
peat,  appeared  as  if  stocked  with  two  distinct 
varieties  of  roses.  The  grower  has  secured  five  first 
prizes  in  open  competition  this  year.  In  one  case 
the  better  colour  was  the  deciding  factor  between 
first  and  second  prizes. 

The  intensification  of  the  colour  is  especially 
marked  in  the  case  of  Marechal  Niel.  In  the  hands 
of  at  least  one  well-known  market  grower  humogen 


FIG.    1 6 

The  radishes  on  the  left  were  treated  with  humogen  and  soil,  those  on 
the  right  being  grown  in  soil  alone.  The  best  dozen  of  the  humogen- 
treated  plants  weighed  6|  ounces  as  against  3!  ounces  from  the 
untreated.  The  second  best  dozen  of  treated  plants  weighed  5^ 
ounces,  while  in  the  other  case  the  second  dozen  plants  were  not 
weighable. 

(Mr.  Holmes,  Tuckswood  Farm,  Norwich.) 


GENERAL  RESULTS  195 

and  soil  is  giving  considerably  better  results  than 
his  own  soil  mixture. 

SCHIZANTHUS. — The  plants  proved  finer  and 
heavier  flowered,  and  the  individual  flowers  were 
larger  than  the  controls. 

SCUTELLARIA  CosxARiCANA. — The  plants  were 
grown  with  humogen  and  soil  as  against  a  complete 
manure.  There  was  differential  improvement  in  the 
case  of  the  humogen-treated  plants  in  root  develop- 
ment, nature  of  foliage,  symmetry,  and  size.  The 
increased  sturdiness  of  growth  was  notable,  while 
the  flowers  were  distinctly  heavier  and  earlier. 

STREPTOCARPUS.  —  Excellent  growth  was  made 
with  glossy  foliage  and  abundance  of  flower. 

SWEET  PEAS. — The  effect  of  humogen  on  sweet 
peas  is  marked.  There  is  increase  in  growth,  height, 
and  length  of  flower-stems,  and  intensification  in  the 
colour  and  veining  of  the  bloom.  The  foliage  is 
healthier  looking  and  deeper  in  tint.  The  Bide 
Challenge  Cup  was  won  this  year  (1915)  by  an 
amateur  at  the  National  Sweet  Pea  Society  Show  by 
blooms  from  plants  grown  with  the  aid  of  humogen. 
The  second  prize  was  also  won  by  a  grower  who  had 
used  humogen.  The  same  grower  (who  got  first 
prize)  has  won  at  different  shows  this  year  five  first 
prizes  and  one  second  prize,  in  every  case  with 
humogen-treated  plants.  In  two  gardens  where 
humogen  was  used  streak  was  absent,  though  un- 
treated plants  collapsed  from  the  disease. 

TOMATOES. — Stimulation  of  growth  is  very  marked 
with  tomatoes.  Rapid  growth  takes  place,  but 
plants  remain  short- jointed  and  small  foliaged, 


196  THE  SPIRIT  OF  THE  SOIL 

setting  and  fruiting  heavily.  According  to  reports 
received  treated  crops  have  frequently  given  double 
the  yield  of  untreated.  Several  growers  state  that 
ripening  is  advanced  by  from  three  to  four  weeks. 
(Photo,  p.  145.) 

TURNIPS. — Several  experiments  have  been  made 
with  turnips.  In  one  of  these,  in  poor  soil,  peat 
increased  the  yield  by  100  per  cent,  over  no  treat- 
ment, by  47  per  cent,  over  artificial  manures,  and 
26  per  cent,  over  dung.  In  another  experiment 
humogen  increased  the  yield  by  121  per  cent,  over 
no  manure,  while  farmyard  manure  gave  an  increase 
of  67  per  cent,  over  none,  and  artificial  manures 
gave  an  increase  of  52  per  cent,  over  none. 

WALLFLOWERS. — Fine  bushy  plants  resulted  from 
treatment.  Masses  of  fibrous  roots  were  formed 
which  transplanted  well,  yielding  plants  that  were 
perfect  mounds  of  bloom. 

WHEAT. — Wheat  treated  on  an  experimental 
scale  in  a  market  garden  with  humogen,  and 
compared  with  the  untreated  garden  soil,  was  taller, 
stronger,  and  greener  than  the  non-treated  wheat. 
It  was  well  in  spike  on  June  15,  and  the  tillering  was 
better,  averaging  twenty-three  ears  as  compared  with 
fifteen.  The  humogen  was  applied  on  the  scale  of  5  cwt . 
to  the  acre,  and  used  as  a  top-dressing.  The  culms 
were  very  much  heavier,  and  the  untreated  plants 
were  in  comparison  very  yellow,  dwarf er,  weaker,  and 
more  backward  in  bloom.  The  plants  showed  a  gain 
of  a  foot  in  height,  and  the  ears  were  i£  inches  longer 
and  fuller.  Unfortunately  both  treated  and  untreated 
plants  were  beaten  down  during  one  of  the  heavy 
storms,  and  the  experiment  could  not  be  concluded. 


CHAPTER  XV 

HINTS  AND  EXPERIMENTS 

IN  this  chapter  I  have  collected  together  the  points 
that  must  be  borne  in  mind  by  those  who  wish  to 
test  humogen  experimentally,  expressing  them  in  the 
briefest  possible  form.  I  have  suggested  a  few  model 
experiments  as  a  guide,  but  naturally  the  most 
interesting  results  will  be  obtained  by  those  who 
design  and  carry  out  experiments  for  themselves. 
In  conducting  experiments  every  fact  observed 
should  be  carefully  noted  down  at  the  time,  and  the 
progress  of  experiments  should  be  recorded  by  photo- 
graphs at  frequent  intervals.  All  dates,  especially 
such  as  that  of  the  first  appearance  of  the  shoot  above 
the  soil,  of  the  first  bloom  and  of  the  first  matured 
fruit  should  be  noted.  Invariably  there  should  be 
control  experiments — that  is,  experiments  in  which 
plants  have  been  treated  without  any  other  differ- 
ence except  for  the  omission  of  humogen.  Valuable 
results  can  also  be  obtained  by  testing  humogen 
against  other  manures. 

MISTAKES  TO  BE  AVOIDED. 

Don't  expect  humogen  to  do  all  the  work  of  the 
gardener.  The  better  the  cultivation,  the  better  the 
results. 

197 


198  THE  SPIRIT  OF  THE  SOIL 

Don't  attempt  to  grow  plants  out  of  their  season 
in  the  open. 

Don't  attempt  to  grow  plants  in  sour  soil.  Lime 
must  be  given  in  this  case  to  render  the  soil  neutral 
or  slightly  alkaline. 

Don't  give  too  much  water.  Pot  plants  do  not 
require  watering  until  the  pots  ring  when  struck. 

Don't  judge  the  water  condition  of  the  soil  by  the 
surface. 

Don't  overcrowd  the  plants,  but  leave  room  for  root 
growth. 

Don't  use  humogen  in  greater  concentration  than 
i  part  in  10,  or  you  will  waste  the  material. 

Don't  be  disappointed  if  a  slight  retardation  is 
evident  at  first  when  using  sterilized  soil. 

Don't  leave  bags  of  humogen  where  they  can  get 
wet.  An  ordinary  dry  garden  shed  is  a  suitable 
place. 

Don't  be  afraid  that  the  humogen  can  injure  plant 
growth. 

Don't  be  afraid  of  the  bacteria  in  humogen.  They 
are  perfectly  harmless. 

Don't  attempt  to  grow  plants  in  rooms  with  coal 
fires  or  gas. 

POINTS  TO  BE  REMEMBERED. 

One  part  of  humogen  to  ten  of  soil  gives  the  best 
results,  with  the  exception  of  bulbs  (monocotyle- 
dons), when  i  in  20  should  be  used. 

Mix  up  your  compost  in  accordance  with  the 
requirements  of  the  varying  species,  using  humogen 
instead  of  leaf  mould  and  dung. 


HINTS  AND  EXPERIMENTS  199 

When  growing  plants  in  moss  and  humogen  ex- 
tract sterilize  the  moss. 

When  possible  mix  humogen  with  the  soil. 

Treat  the  plants  with  humogen  from  the  seed-leaf 
stage. 

When  using  moss,  water  once  a  week  with  a  coffee- 
coloured  extract  of  humogen.  Use  plain  water  at 
other  times. 

When  using  as  a  top-dressing  incorporate  the 
humogen  as  deeply  as  possible  in  the  soil. 

When  preparing  the  ground  lightly  dig  in  the 
humogen  some  few  days  before  sowing. 

Apply  humogen  to  the  land  early,  so  as  to  give 
the  bacteria  time  to  multiply  in  the  soil  while  it 
is  moist. 

On  poor  ground  use  at  least  10  cwt.  per  acre. 

For  kitchen  garden  crops  it  pays  to  use  liberally. 
Eight  to  ten  pounds  per  rod  should  suffice.  Roses 
and  flower  borders  the  same. 

If  you  wish  to  co-operate  in  advancing  soil  bac- 
teriology keep  accurate  accounts  of  all  you  do,  and 
especially  measure  the  humogen  employed  and  the 
resulting  produce.  The  model  experiments  are  a 
guide  how  to  keep  results. 

Remember  if  you  don't  get  results  to  write  direct 
to  Mr.  Alfred  Machen,  48,  Frances  Road,  Windsor, 
giving  full  details  of  what  you  have  done.  Either 
failure  is  due  to  avoidable  error,  or  your  experience 
will  help  to  advance  knowledge. 


200  THE  SPIRIT  OF  THE  SOIL 

MODEL  EXPERIMENT  I. 

Radishes. 

The  French  breakfast  radish  is  a  convenient  plant 
for  a  preliminary  experiment.  Use  two  small  boxes 
about  3  inches  deep.  Fill  one  with  your  garden  soil 
or  loam  obtainable  from  a  seedsman.  To  the  other 
box  add  humogen,  using  one-ninth  of  the  bulk  of  the 
soil  (conveniently  measured  by  a  teacup) .  Mix  the 
humogen  and  soil  well.  Plant  the  same  number  of 
seeds  in  each  box  about  ij  inches  apart  and  about 
J  inch  deep.  Water  thoroughly,  interchanging  the 
position  of  the  boxes  weekly,  so  as  to  insure  similar 
treatment.  A  window-ledge  or  a  site  in  the  open 
garden  is  suitable,  but  in  the  former  case  care  must 
be  taken  with  the  watering,  as  in  such  conditions 
the  soil  dries  rapidly.  The  best  plan  is  to  plunge 
the  box  up  to  the  edge  in  the  soil,  when  watering 
will  be  reduced  to  a  minimum. 

The  radishes  should  be  pulled  when  ready  for 
eating  from  both  boxes  at  once,  and  the  following 
points  noted : 

1.  Number  of  plants  in  each  box. 

2.  Weight  of  complete  plants  in  each  box. 

3.  Weight  of  edible  portion  in  each  box. 

4.  Divide  weights  in  each  box  by  number  of  plants 
in  each  box  to  get  a  comparison  of  the  average  weight 
of  the  roots. 

5.  Notice  the  quality  as  well  as  the  quantity. 

6.  Determine  percentage  increase  by  multiplying 
the  weight  in  the  box  treated  with  humogen  by  100. 


HINTS  AND  EXPERIMENTS  201 

Divide  this  by  the  weight  of  the  untreated  plants, 
and  subtract  100  from  the  answer. 

Thus,  to  work  out  the  percentage  increase  in  the 
humogen-treated  beans  obtained  by  Mr.  Holmes, 
and  described  in  the  chapter  on  "  The  Testing  of 
Humogen,"  one  would  calculate  as  follows: 

x  100  _  151  (half  ounces)  x  100 
8J  8  1  (half  ounces) 


.-.  Percentage  increase  =  186*5  ~  *oo  =  86*5  per  cent. 

NOTE  that  experiments  with  radishes  can  be  con- 
ducted in  the  open  at  any  time  between  the  middle 
of  March  and  the  first  week  in  September.  The 
plants  can  be  grown  in  a  greenhouse  or  in  a  light 
and  airy  room  at  any  time  of  the  year. 

MODEL  EXPERIMENT  II. 

Primula  (any  Variety). 

Primula  plants  ready  for  their  final  potting  are 
easily  obtained  in  the  early  autumn.  The  new  pots 
should  be  filled  (i)  with  good  potting  soil,  as  recom- 
mended by  nurserymen  from  whom  it  may  be 
obtained  ;  (2)  with  some  rich  mixture  such  as  that  de- 
scribed in  the  chapter  on  "  The  Testing  of  Humogen," 
as  used  at  Kew,  or  according  to  what  the  experi- 
menter regards  as  the  best  possible  obtainable; 
(3)  the  good  potting  mixture  used  for  (i),  with  one- 
ninth  of  humogen  well  mixed.  From  this  time 
ordinary  cultivation  is  all  that  is  necessary. 


202  THE  SPIRIT  OF  THE  SOIL 

NOTE. — (i)  The  comparative  growth  of  the  plants 
at  various  stages. 

(2)  The  development  of  the  root. 

(3)  The  colour  and  thickness  of  foliage. 

(4)  The  date  at  which  blooms  first  appear. 

(5)  The  date  at  which  the  plants  stop  blooming. 

(6)  The  number  of  blooms  obtained  from   each 
plant  throughout  the  season. 

(7)  The  size  and  colour  of  individual  blooms. 

MODEL  EXPERIMENT  III. 

Moss  Culture. 

Sterilize  any  variety  of  moss  by  heating  it  in  steam. 
The  moss  should  not  be  boiled  in  water.  The  best 
rough  way  of  sterilizing  the  moss  is  to  cover  the 
bottom  of  a  large  saucepan  with  \  inch  of  water. 
Then  cover  the  bottom  of  the  saucepan  2  inches  deep 
with  well-broken  clean  road-metal,  or  some  similar 
substance  to  prevent  the  water  from  reaching  the 
moss.  Fill  the  rest  of  the  saucepan  with  the  moss, 
and  boil  well  for  a  quarter  of  an  hour.  Avoid  heating 
to  dryness,  and  if  necessary  add  water.  The  sauce- 
pan should  be  covered.  Better  still  an  ordinary 
kitchen  steamer  should  be  used.  Nearly  any  plant 
can  be  used  for  moss  culture,  but  the  following  are 
recommended :  Potatoes,  bulbs  of  all  sorts,  ferns. 

All  that  is  necessary  is  to  water  the  plant  once  a 
week  with  humogen  extract.  Use  the  proportion  of 
i  pint  of  humogen  to  2  gallons  of  water.  To  prepare 
the  liquid  mix  the  humogen  in  a  jug  with  water  not 
warmer  than  can  easily  be  drunk.  Stand  over 


HINTS  AND  EXPERIMENTS  203 

night,  and  decant  the  liquid  in  the  morning.  Water 
the  moss  once  a  week  with  humogen  extract,  and 
in  between  times  with  ordinary  tap-water. 

NOTE.— (i)  The  weight  of  the  bulb  when  planted 
and  its  weight  at  the  end  of  the  season. 

(2)  The  same  points  as  in  the  primula  and  radish 
experiments. 

(3)  The  weight  of  the  crop  when  tubers  are  grown. 

MODEL  EXPERIMENT  IV. 
"  Top-Dressing." 

The  effect  of  humogen  may  be  tried  on  any  plants 
or  grass  growing  in  the  garden  at  any  time  from 
March  to  September.  Use  4  to  6  ounces  to  the 
square  yard,  and  work  well  into  the  soil.  On  grass 
spread  the  humogen  over  the  surface.  For  this 
experiment  humogen  should  be  applied  only  in 
plots.  Thus,  half  a  bed  should  be  treated  and  the 
other  half  not  treated,  so  that  improvements  result- 
ing may  be  noted.  Apparently  inconsistent  results 
must  be  expected  in  this  experiment,  as  humogen 
will  not  usually  force  a  plant  into  fresh  growth  if  the 
normal  resting  stage  has  been  reached  for  the  season. 

NOTE  all  such  points  as  described  in  the  primula 
and  radish  experiments,  and  especially  compare 
the  condition  of  the  treated  and  the  untreated  plants. 

NOTE  TO  FARMERS  AND  GARDENERS. 

As  a  measure  of  prudence  it  would  be  wise  for 
farmers  and  gardeners  wishing  to  experiment  with 
humogen  on  a  large  scale  to  write  direct  to  Mr.  Alfred 


204 


THE  SPIRIT  OF  THE  SOIL 


Machen,  48,  Frances  Road,  Windsor,  describing 
accurately  the  nature  of  the  soil,  what  has  been 
recently  grown  in  it,  and  the  crops  on  which  it  is 
proposed  to  use  humogen.  A  report  should  be  sent 
in  at  once  if  negative  results  are  obtained. 

MODEL  FORM  FOR  RECORDING  RESULTS. 

HUMOGEN  EXPERIMENTS. 

Date. . 


Crops. 


Quantity. 


How  applied. 


Result :  Weights 
where  possible. 


General  Remarks. 


Name  and  Address  of  Experimenter. 


NOTE. — Where    possible,   supply  photographs.     Address    all 
remarks  to  Mr.  Alfred  Machen,  48,  Frances  Road,  Windsor. 


APPENDIX  A 

NITROBACTERINE  AND  LEGUMINOUS  PLANTS 

IN  connection  with  the  use  of  nitrobacterine,  in  over 
80  per  cent,  of  the  reports  made  to  Professor  Bottomley 
there  was  evidence  that  the  use  of  the  material  had 
shown  a  distinct  advantage  gained  by  the  crops 
through  inoculation.  As  a  method  similar  to  Professor 
Bottomley's  is  still  being  employed  in  America,  the 
original  American  method  having  been  abandoned,  the 
following  reports,  which  were  published  by  Country 
Life  in  a  pamphlet,  Seed  and  Soil  Inoculation  for 
Leguminous  Crops,  in  1908,  may  be  of  interest.  It  has 
been  found  since  that  many  of  the  failures  were  due 
to  preventable  causes.  The  successes  obtained,  however, 
remain  of  considerable  historic  and  practical  interest. 
As  in  the  original  pamphlet,  the  reports  are  grouped 
by  counties. 

CORNWALL. 

MARAZION — Peas. — The  peas  were  a  great  success. 
Inoculation  of  soil  and  seed  returned  a  good  30  per  cent, 
more  than  only  seed  inoculation,  and  the  seed  inoculation 
showed  a  good  20  per  cent,  better  crop  than  the  farmyard 
manured  peas.  Inoculation  in  both  cases  rendered  a 
fortnight  earlier  marketing  possible  over  the  manured. 

205 


2o6  THE  SPIRIT  OF  THE  SOIL 

CHESHIRE. 

CHESTER — Peas. — Taking  a  piece  of  poor  ground  in  an 
old  garden  we  planted  one  portion  with  inoculated  seed, 
and  in  another  portion  inoculated  the  soil.  Against  this 
and  adjoining  we  sowed  the  same  kind  of  peas  untreated, 
half  upon  ground  treated  with  ordinary  farmyard 
manure,  the  other  half  with  a  little  bone  manure  in 
addition.  As  regards  the  result  it  was  easily  discernible 
which  peas  had  been  treated,  the  foHage  being  stronger, 
and  the  pods  larger  and  more  freely  produced  than 
those  grown  on  the  manured  ground. 

CHILDER  THORNTON — Clover. — They  have  just  begun 
cutting  the  oats,  and  are  very  pleased  with  the  inoculated 
clover;  it  is  almost  too  good,  very  strong  plants. 

HALE — Sweet  Peas. — The  inoculation  of  my  sweet  peas 
has  been  an  immense  success.  Unfortunately  the  un- 
favourable weather  this  summer  prevented  me  showing 
in  London  on  July  16,  but  with  blooms  2 J  inches  across, 
and  stems  18  inches  long,  in  addition  to  numerous  four 
blooms  per  stem  (very  few  less  than  three),  I  can  say  with 
confidence  that  there  were  none  better.  Whilst  in  this 
district  and  Manchester  they  have  been  generally 
remarked  upon.  From  the  very  commencement  of 
operations  the  inoculated  seeds  showed  more  vigour  than 

the  others. 

DORSET. 

WEYMOUTH — Peas. — For  experiment  with  peas  I 
sowed  one-third  without  and  two-thirds  with  culture 
treatment  to  seeds  previous  to  planting.  Results  as 
follows : 

1.  Stages  of  early  growth  little  difference. 

2.  As  soon  as  flower  blooms  appeared  the  haulms  of 
"  culture  "  gained  considerably  in  strength,  height,  and 
show  of  blossom. 


APPENDIX  A  207 

3.  Pods  of  "  culture  "  fairly  20  per  cent,  better — both 
in  size  and  quantity. 

4.  Flavour  decidedly  superior  to  "  non  "-treated. 

5.  A  few  haulms  of  "  culture  "  bore  pods  of  far  larger 
size  than  the  type. 

DEVON. 

TAVISTOCK — Clover. — The  inoculated  clover  was  taller 
by  3  inches  than  the  uninoculated. 

DENBIGHSHIRE. 

WREXHAM — Sweet  Peas. — Inoculation  has  been  quite 
a  success.  The  flowers  are  greater  in  number  by  at  least 
20  per  cent,  than  those  not  treated,  and  the  size  of  the 
flowers  is  much  larger. 

ESSEX. 

EPPING — Peas. — First  sown  peas,  inoculated,  a  fine 
crop  with  haulms  of  great  thickness,  and  fruit  large  and 
juicy.  Second  sowing,  uninoculated,  results  very  poor, 
haulm  thin  and  weakly,  crop  almost  useless.  The 
ground  on  which  first  crop  was  sown  had  had  no  peas 
on  it  for  several  years,  whereas  the  ground  on  which 
second  crop  was  sown  had  had  peas  grown  on  it  in  the 
previous  year. 

CHAPPEL — Sweet  Peas. — The  inoculating  material  you 
sent  me  was  a  distinct  success.  The  sweet  peas  started 
to  blossom  earlier  than  the  non-inoculated,  and  grew 
2  feet  higher.  I  gained  three  prizes  with  them  in  open 
classes  at  local  shows.  My  soil  is  very  light  and  shallow, 
and  was  never  cultivated  until  two  years  ago,  and  num- 
bers of  people  have  been  surprised  at  my  display  of 
sweet  peas  on  such  poor  ground. 

WOODFORD  —  Peas.  —  Seeds  treated;  plants  also 
watered  with  solution  at  later  period  of  growth.  The 


208  THE  SPIRIT  OF  THE  SOIL 

treated  peas  show  a  very  much  more  vigorous  growth, 
and  much  better  yield  of  fruit. 

HORNCHURCH — Peas. — The  row  which  I  treated  with 
your  preparation  seems  generally  stronger  and  certainly 
earlier  than  the  others.  As  regards  earliness,  the  row 
treated,  although  planted  out  a  fortnight  later,  began  to 
flower  before  those  not  treated. 

GLOUCESTERSHIRE. 

STAUNTON — Vetches. — The  inoculated  were  greener 
and  thicker  than  those  not  treated. 

Broad  Beans. — The  inoculated  were  up  a  week  and  a 
half  before  those  not  treated,  and  were  very  much 
greener  and  more  weight. 

2  rows  inoculated,  65  yards  long,  gave  4j  pots. 
2     „    not  inoculated      ,,       „       ,,       3      „ 

a  gain  nearly  half  as  much  again,  ij  pots,  or  52  pounds, 
a  pot  being  42  pounds. 

Peas. — The  inoculated  peas  were  a  great  success.  They 
were  from  the  beginning  very  much  greener  than  those 
not  dressed,  and  the  pods  were  J  to  i  inch  longer,  and 
much  larger  peas.  I  had  the  best  crop  of  peas  round 
here  for  2  or  3  miles,  and  was  the  first  to  sell  to  the 
greengrocers  in  Gloucester  in  quantities.  From  a 
quarter  of  an  acre  planted  with  i  bushel  inoculated  seed 
I  picked  33!  pots  (42  pounds  to  the  pot),  selling  them 
for  £7  1 8s.  gd.  From  a  quarter  of  an  acre  planted  with 
i  bushel  non-inoculated  seed,  but  dressed  with  i  cwt. 
superphosphate  and  J  cwt.  sulphate  of  potash,  I  picked 
only  14  pots,  selling  them  for  £2  5s.  6d.  I  also  planted 
a  quarter  of  an  acre  with  i  bushel  inoculated  seed,  and 
manured  with  J  cwt.  superphosphate  and  \  cwt.  sulphate, 
and  picked  54^  pots. 


APPENDIX  A  209 

This  village  is  composed  of  about  80  small  holdings 
from  2  to  4  acres,  and  most  of  the  people  grow  market 
garden  stuff.  They  were  surprised  at  me  being  able  to 
pick  so  much  off  the  small  amount  of  ground.  I  shall 
be  pleased  to  obtain  more  inoculation  material  next  year, 
when  I  want  to  try  it  on  some  heavy  clay  land  which  is 
very  poor,  and  has  been  laid  down  two  years. 

GUERNSEY. 

RAMEE — Runner  Beans. — The  beans  were  grown  with 
the  material  you  were  kind  enough  to  send  us,  and  we 
may  say  that  we  have  never  had  a  better  and  earlier 
crop.  The  seeds  came  up  very  strong,  and  the  leaves 
had  a  nice  dark  colour.  We  picked  the  first  beans  six 
weeks  after  sowing. 

A  more  detailed  report  states:  On  October  5,  1906, 
we  planted  the  house  with  beans,  which  did  not  crop  very 
well.  The  house  is  200  feet  long  and  30  feet  wide.  This 
crop  was  finished  on  February  21,  1907.  We  then 
cleansed  the  house,  burned  some  sulphur,  washed  the 
glass,  and  trenched  the  ground  about  18  inches  deep, 
and  worked  in  2  cwt.  pulverized  chalk,  and  ij  cwt. 
Cross's  organic  manure.  We  replanted  the  house  with 
inoculated  seed  on  February  22,  and  our  first  beans  were 
sent  to  market  on  April  8.  We  can  assure  you  beans 
have  never  before  done  so  well  in  our  ground. 

HANTS. 

WINCHESTER — Peas. — The  inoculated  peas  are  grow- 
ing and  bearing  well,  especially  as  none  of  them  were 
manured.  My  opinion  is  that  inoculation  is  a  great 
help  on  such  poor  soils  as  mine. 

14 


210  THE  SPIRIT  OF  THE  SOIL 

JERSEY. 

ST.  OUEN'S — Lucerne. — The  inoculated  seed  came  up 
better  than  the  untreated,  and  the  crop  is  now  a  lot 
thicker  and  of  more  even  growth. 

Peas. — I  found  the  culture  increased  the  pea  crop  a 
great  deal,  and  they  were  at  least  a  week  earlier  than 
the  non-inoculated.  The  land  is  very  poor  gravelly  soil. 

KENT. 

FAVERSHAM — Clover. — Culture  applied  by  being  mixed 
with  earth,  then  spread  and  harrowed.  Treated  half  acre 
yielded  2j  waggon  loads  of  clover  fodder;  untreated, 
2  loads.  The  clover  on  the  treated  part  was  stouter  and 
larger  than  on  untreated.  Soil  rather  thin  near  the  chalk. 

BECKENHAM — Sweet  Peas. — I  have  not  grown  sweet 
peas  before  this  year,  and  therefore  cannot  compare  with 
any  previous  results.  I  may  say,  however,  that  my  plants 
have  excited  the  admiration  of  my  friends.  I  treated 
the  seeds  with  your  culture,  and  some  of  the  plants  have 
run  up  to  8  feet  in  height.  The  flower-stalks  have  been 
in  some  cases  16  inches  long,  and  while  threes  have  been 
general,  there  have  been  several  fours,  the  blooms  being 
of  fine  size. 

LYMINGE — Peas. — The  peas  greatly  benefited  by  your 
inoculating  process.  I  had  as  many  as  13  peas  in  a  pod, 
and  the  general  run  of  the  pods  contained  8  or  9. 

CANTERBURY — Beans. — Strip  20  furrows  wide  through 
centre  of  field  sown  with  seed  not  dressed  yielded 
ii  bushels  5  gallons;  strip  20  furrows  wide  (above)  sown 
with  inoculated  seed  yielded  14  bushels  i  gallon ;  similar 
strip  (below)  yielded  14  bushels  7  gallons.  The  whole 
of  the  field  where  seed  was  treated  gave  a  yield  of 
6  quarters  2  bushels,  which  was  very  good  indeed  for  such 


APPENDIX  A  211 

poor  land,  and  speaks  very  well  indeed  for  the  farms  you 
so  kindly  set  to  work  on  our  account.  Now  that  this 
has  been  such  a  success,  may  I  hope  you  will  kindly 
furnish  me  with  some  more  bacteria  for  the  coming  year, 
or  tell  me  how  I  can  obtain  it. 

LANCASHIRE. 

GRAPPENHALL — Beans. — I  had  a  bed  inoculated  and 
one  without.  In  early  stages  those  inoculated  seemed 
the  stronger  plants,  but  at  maturity  there  did  not  seem 
much  difference ;  but  I  shelled  them  myself,  and  consider 
those  inoculated  yielded  fully  30  per  cent,  more  than 
those  non-inoculated.  I  planted  them  in  ground  that 
had  no  manure  for  two  years,  and  I  consider  the  results 
very  satisfactory. 

WHALLEY  RANGE — Peas. — The  plot  treated  with  cul- 
ture was  approximately  a  fortnight  in  advance  of  a 
similar  plot  planted  with  untreated  seed.  The  plants  are 
exceptionally  good. 

Sweet  Peas. — Seeds  which  were  treated  did  exception- 
ally well,  growing  plants  a  third  higher  than  similar 
seeds  untreated.  Also  on  the  plants  which  have  been 
treated  with  culture  I  notice  an  unusually  large  pro- 
portion of  flowers,  with  fours  and  occasionally  fives  on 

one  stem. 

LEICESTERSHIRE. 

DESFORD — Peas. — The  crop  is  20  per  cent,  better  on 
the  untreated  peas.  The  haulm  is  much  more  robust 
and  healthier  in  appearance  also,  and  flowers  are  still 
being  produced,  while  the  non-inoculated  plot  is  over. 

LINCOLNSHIRE. 

WOODHALL  SPA — Green  Peas  and  Sweet  Peas. — Inocu- 
lated were  most  successful;  uninoculated  but  a  poor  crop. 


212  THE  SPIRIT  OF  THE  SOIL 

Scarlet  Runners  promise  a  full  crop,  though  growing  in 
very  poor  sandy  soil — in  fact,  little  more  than  sand. 
They  are  certainly  as  prosperous,  if  not  more  so,  than 
the  non-inoculated  plants  in  manured  soil. 

MIDDLESEX. 

WHITTON— Peas.— The  results  of  treating  the  peas 
with  bacteria  have  been  eminently  satisfactory.  My 
experience  was  as  follows : 

"  Gradus,"  without  inoculation,  a  fair  crop,  but  they 
were  soon  over. 

"  Sutton's  Ai,"  inoculated,  heavy  crop,  with  abun- 
dance of  well- filled  pods. 

"  Veitch  Perfection/'  inoculated,  a  very  heavy  haulm 
packed  with  pods,  so  much  so  that  the  weight  of  the  crop 
broke  the  haulm  down,  though  they  were  "  re-sticked." 

"  Exhibition,"  inoculated,  showed  a  wonderful  crop; 
these  were  so  prolific  that  the  haulms  broke  down  under 
their  weight  of  produce,  growing  6  to  7  feet  high,  with 
pods  6  and  7  inches  long. 

All  the  above  were  sown  in  new  ground,  having  never 
grown  anything  before  except  grass.  I  estimate  the 
produce  from  inoculation  was  from  30  to  40  per  cent, 
more  than  from  the  untreated  seed.  I  was  told  that  my 
peas  were  the  finest  in  the  district. 

HARROW — Runner  Beans. — I  tried  your  system  of 
inoculation  upon  some  runner  beans  during  the  past 
season,  and  was  surprised  at  the  results.  The  inoculated 
beans  yielded  45  to  50  per  cent,  more  in  weight  than 
those  grown  under  ordinary  conditions. 

NORFOLK. 

NORWICH — Peas. — The  inoculated  peas  were  three 
weeks  earlier  for  market,  and  decidedly  50  per  cent,  more 
prolific  than  the  non-inoculated. 


FIG.    17 

The  number  of  blooms  thrown  and  the  size  and  colour  of  the  individual 
blooms  are  the  main  results  obtained  by  the  application  of  humogen 
to  the  primula.  The  above  photograph  shows  two  specimens  of 
Primula  Keivensis.  Both  were  planted  in  ordinary  potting  compost, 
but  the  one  on  the  right  was  watered  continually  with  humogen 
extract,  while  the  one  on  the  left  was  watered  with  guano  extract. 
(Grown  at  the  Royal  Gardens,  Kew.) 


APPENDIX  A  213 

MARSH  AM — Peas. — We  made  our  experiments  with 
the  greatest  care,  inoculating  six  rows  of  peas,  planting 
different  sorts.  In  every  case  the  yield  from  the  inocu- 
lated rows  (we  planted  fifteen  rows  in  all)  is  three  times  as 
good  as  from  the  uninoculated,  the  pods  hung  in  clusters, 
and  the  yield  was  excellent,  and  earlier  than  we  have 
ever  had  before. 

SWAFFHAM  —  Peas.  —  Result  excellent.  An  exceed- 
ingly heavy  crop.  Beyond  this,  the  most  noticeable 
features  about  the  different  varieties  are  that  the  inocu- 
lated have  continued  bearing  much  longer  than  usual,  and 
the  almost  complete  freedom  from  maggots  in  the  pods, 
and  from  any  appearance  of  mildew  on  the  foliage. 

NOTTS. 

SOUTHWELL — Clover. — The  clover  seed  was  sown  on 
land  which  before  had  failed  to  produce  a  crop.  The 
treated  seed  has  come  up  very  thick,  much  better  than 
the  untreated,  and  there  is  a  fine  crop. 

SHROPSHIRE. 

OSWESTRY — Vetches. — Where  the  vetches  were  dressed, 
your  dressing  seems  to  have  acted  wonderfully,  and  a 
fine  crop  has  resulted. 

Peas. — Our  inoculation  experiment  has  turned  out  a 
complete  success.  We  have  had  a  splendid  crop.  The 
inoculated  crop  overtook  another  crop,  not  inoculated, 
by  four  weeks. 

BRIDGNORTH — Peas. — The  bacteria  culture  was  very 
successful.  The  seed  peas  were  treated  strictly  accord- 
ing to  instructions,  and  I  had  a  check  lot  of  untreated 
peas  sown  parallel  (and  4  feet  away)  to  the  treated  peas. 
The  haulm  of  the  treated  peas  grew  very  large,  and  the 
foliage  was  fine,  and  remained  clean  and  healthy.  The 


214  THE  SPIRIT  OF  THE  SOIL 

plants  blossomed  very  freely,  and  very  many  pods  were 
produced.  In  the  case  of  the  untreated  peas  the  pods 
were  few,  and  did  not  fill  well,  and  the  peas  produced 
were  not  as  sweet  as  those  on  the  treated  peas.  I  gave 
some  of  the  culture  to  a  friend,  who  was  sceptical  and 
gave  a  grudging  consent  to  its  use.  He  has  never  before 
been  able  to  grow  a  good  crop  of  peas  in  his  garden. 
This  year  he  says:  "  The  only  things  to  do  any  good  are 
the  peas,"  so  you  may  rely  on  it  that  the  culture  has  done 
a  lot  of  good. 

STAFFORDSHIRE. 

TAMWORTH  AGRICULTURAL  COLLEGE. — Clover  sown 
with  rye-grass  inoculation  gave  an  increase  of  about 
15  per  cent.  Tares  inoculated  showed  an  increase  of 
about  10  per  cent. 

SOMERSET. 

BATH — Sweet  Peas. — The  inoculation  with  sweet  peas 
was  quite  successful,  the  inoculated  seed  producing  the 
best  flowers  that  I  have  ever  had,  and  much  stronger 
than  the  seed  which  was  not  inoculated.  Inoculation 
was  by  watering  the  planted  seeds.  My  soil  is  loam,  and 
always  kept  well  manured. 

SURREY. 

HINDHEAD — Sweet  Peas. — The  inoculation  experiment 
has  been  very  satisfactory.  We  planted  the  inoculated 
sweet  peas  in  poor  sandy  soil  which  had  not  previously 
borne  flowers — dug-up  bracken  and  heath  land.  The 
flowers  have  been  beautiful  and  plentiful,  and  at  this 
date,  when  the  non-inoculated  peas  are  over,  the  inocu- 
lated are  still  plentiful  and  seem  to  have  an  unusually 
sweet  odour , 

SUTTON — Sweet  Peas. — Some  freshly  dug  meadow-land 
was  sown;  one  half  the  seeds  were  treated  with  the  solu- 


APPENDIX  A  215 

tion  and  the  young  plants  watered  as  advised,  the  other 
half  untreated.  The  treated  seeds  produced  the  finest 
show  of  flowers  we  have  ever  raised,  but  the  young  plants 
from  the  undressed  seeds  were  unfortunately  so  badly 
attacked  by  slugs  and  snails  as  to  make  comparison 
useless.  Some  of  the  solution  was  given  to  a  gardener  at 
Carshalton.  He  divided  his  seed  into  two  lots — treated 
and  untreated.  His  soil  was  a  light  loam  on  chalk.  The 
untreated  seeds  produced  a  good  show  of  flowers,  but 
the  treated  seeds  did  far  better.  He  estimates  that  the 
yield  of  flowers  was  increased  by  about  a  third. 

WOKING — Peas. — The  "  pea  culture  "  is  a  great  suc- 
cess. Those  peas  watered  with  the  solution  have  yielded 
in  an  astonishing  manner — the  yield  has  been  more  than 
double. 

Peas. — I  planted  the  inoculated  peas  on  land  that  has 
not  been  manured  for  many  years,  and  had  a  crop  of 
peas  quite  equal  to  those  grown  by  a  friend  on  manured 
soil. 

Broad  Beans. — I  had  similar  results  with  broad  beans, 
which  produced  a  later  growth  almost  equal  to  the  first. 

REDHILL — Peas. — From  i  pint  of  peas  inoculated  the 
yield  was  at  the  very  least  35  to  40  per  cent,  more  than 
from  the  pint  not  treated.  We  are  still  gathering  from 
the  inoculated  peas,  and  several  pods  when  opened  show 
8  and  9  peas  in  each. 

Scarlet  Runners. — The  inoculated  scarlet  runners  are 
quite  a  sight,  reaching  the  tops  of  the  8  and  9  feet  sticks, 
and  I  have  had  to  run  strings  (like  they  do  hops)  to  help 
the  runners.  The  blossoms  are  a  wonderful  sight,  and 
the  lower  ones  are  showing  runners  of  8  to  10  on  one 
stem. 

KNAPP  HILL — Beans. — I  am  pleased  to  say  that  inocu- 
lation has  been  a  splendid  success.  I  treated  half  of 


216  THE  SPIRIT  OF  THE  SOIL 

each  row  of  broad  beans  with  the  solution  direct  to  the 
roots.  The  photos  I  send  you  show  the  comparative 
sizes  of  the  bean  pods  at  the  time  I  commenced  to  pick 
them.  The  inoculated  ones  were  7 J  to  8  inches  long ;  the 
non-inoculated  only  4!  inches  long.  I  left  four  of  the 
best  plants  in  both  inoculated  and  non-inoculated  plots 
to  grow  to  maturity.  The  average  length  of  the  pods 
from  the  inoculated  plants  was  n  inches,  averaging 
8  beans  to  the  pod;  the  non-inoculated  8J  inches  long, 
with  6  beans.  The  inoculated  beans  were  quite  three 
weeks  earlier  than  the  others. 

Peas. — The  peas  were  treated  in  the  same  way,  and 
inoculation  was  equally  successful.  The  inoculated  were 
ready  quite  two  weeks  before  the  others.  My  garden  is 
old  orchard  land,  and  the  ground  received  no  manure 
other  than  that  from  the  grass  which  was  trenched  in 
about  June,  1906. 

SUSSEX. 

BATTLE — Clover. — I  sprayed  part  of  a  field  of  grass, 
cut  over  each  year  then  pastured,  with  the  culture 
solution.  Now  the  sprayed  part  shows  a  great  deal 
more  white  clover  than  the  rest  of  the  field.  On  a 
piece  of  very  poor  land  of  7-year-old  pasture  I  sowed 
inoculated  white  clover  seed.  The  result  has  been  a 
great  improvement  in  the  clover  compared  with  other 
portion  of  the  field,  which  had  formerly  the  best 
clover. 

BRIGHTON — Peas. — We  planted  the  inoculated  peas  in 
the  poorest  ground  we  possess,  and  they  have  done 
exceedingly  well. 

Sweet  Peas. — We  also  sowed  some  inoculated  sweet 
peas  on  a  cinder  path  at  the  top  of  a  low  wall,  and  they 
have  grown  and  blossomed  very  freely,  and  looked  very 


APPENDIX  A  217 

nice  hanging  over  and  covering  the  wall.  Our  friends 
have  been  quite  astonished  to  see  them  growing  in 
cinders. 

WILTSHIRE. 

CHIPPENHAM — Peas. — The  experiments  have  much  ex- 
ceeded my  expectations.  I  applied  the  culture  at  three 
different  periods — at  planting  seed,  and  twice  during 
growth,  on  a  piece  of  remarkably  poor  land.  They  grew 
half  as  high  again  as  usual,  strong  haulm,  of  lovely  deep 
green,  and  simply  smothered  with  blossom;  peas  large 
and  well- filled  pods — double  the  usual  crop. 

Sweet  Peas,  treated  in  same  manner  as  peas,  have  been 
the  admiration  and  envy  of  my  neighbours,  growing 
from  8  to  9  feet  high,  and  literally  a  feast  of  blossom, 
with  stems  12  inches  and  more  in  length;  in  bloom  early 
in  June,  and  are  still  (August  26)  making  a  brave  show. 
It  is  truly  a  wonderful  discovery  this  microbe,  and  bids 
fair  to  revolutionize  ideas  of  gardening. 

WORCESTERSHIRE. 

EVESHAM — Peas. — I  am  sorry  I  am  unable  to  give  you 
accurate  comparative  results  on  inoculated  and  un- 
inoculated  plots  owing  to  reasons  given  below,  but  in 
comparison  with  my  neighbours  I  cropped,  through  your 
assistance,  the  best  return  on  my  peas  in  the  immediate 
neighbourhood,  and  they  were  picked  quite  ten  days 
earlier  than  others  who  planted  on  the  same  day. 
Though  the  land  where  they  were  grown  is  extremely 
good  "  black  soil,"  for  some  reason  it  will  not  grow  peas, 
and  this  is,  I  believe,  the  first  time  anyone  has  matured 
a  crop  on  it. 

Lucerne. — I  have  grown,  with  the  help  of  your  bacteria, 
a  lucerne  crop  far  above  the  average. 


2i8  THE  SPIRIT  OF  THE  SOIL 

YORKSHIRE. 

BRADFORD — Sweet  Peas. — The  sweet  pea  rows  which 
I  inoculated  twice  with  your  bacteria  have  been  an  eye- 
opener  to  all  the  other  sweet  pea  growers  in  this  district. 
The  ground  has  had  no  manure  for  3  years,  but  had  a 
good  top-dressing  of  lime  2  years  ago.  The  foliage, 
bloom,  and  height  of  the  plants  are  far  superior  to  others 
grown  in  same  district  which  have  been  fed  with  arti- 
ficials and  farmyard  manure. 

Peas. — On  culinary  peas  the  result  has  been  mar- 
vellous. The  haulm  was  very  large  and  thick,  and  the 
pods  very  large  and  of  a  lovely  dark  green  colour. 

SHEFFIELD — Runner  Beans. — Inoculated  and  non- 
inoculated  rows  were  grown  in  soil  which  had  had  no 
manure  for  10  years.  The  produce  from  both  lots  was 
carefully  weighed,  and  showed  an  increase  of  inoculated 
over  non-inoculated  of  43  per  cent.  Better  beans  were 
not  to  be  found  in  the  neighbourhood. 

Peas. — The  peas  were  grown  on  clay  soil.  Equal 
quantities  of  inoculated  and  non-inoculated  peas  were 
sown,  and  yielded:  Inoculated,  631  pods;  non-inoculated, 
433  pods — a  gain  of  45-7  per  cent.  The  inoculated  pods 
were  longer  and  fuller,  and  &  fortnight  earlier. 

Sweet  Peas. — The  inoculated  sweet  peas  bloomed 
remarkably  well,  and  were  the  best  in  the  neighbourhood. 
Nurserymen  and  market  gardeners  came  from  miles 
round  to  see  them.  They  carried  off  Firsts  wherever 
they  were  shown,  and  the  proceeds  from  the  sale  of 
flowers  were  abnormal. 

SCOTLAND. 

KELSO — Peas. — Three-quarters  of  a  pound  of  inocu- 
lated pea  seed  yielded  more  than  i  J  pounds  uninoculated ; 


APPENDIX  A  219 

the  inoculated  peas  had  larger  pods,  were  better  filled,  of 
finer  flavour,  and  more  uniform  in  shape  than  the  un- 
inoculated.  The  inoculated  peas  gained  the  second 
prize  at  the  District  Show. 

MELSETTER — Clover. — I  put  the  inoculation  liquid  on 
about  a  quarter  of  an  acre  of  grass  and  clover  as  a  top- 
dressing.  In  about  a  week  I  could  see  an  improvement, 
and  it  (the  clover)  was  far  higher  and  thicker  than  the 
rest  of  the  field  right  on  until  it  was  cut.  There  was 
double  the  quantity  on  it,  and  it  was  the  same  with  the 
aftermath;  it  came  up  the  second  time  far  thicker  and 
stronger  than  the  rest  of  the  field. 

WORMIT  (FIFE)— Peas.— Of  those  that  have  already 
come  to  maturity,  I  find  that  the  pods  from  the  inoculated 
seed  are  more  numerous  and  much  better  filled  than  the 
pods  from  seed  not  treated,  the  ratio  of  produce  being 
about  2  to  i. 

Beans. — Of  the  beans  I  cannot  yet  speak  with  cer- 
tainty, as  the  crop  is  so  late  this  year,  but  the  pods  of  the 
treated  portion  appear  to  be  filling  up  much  better  than 
the  rest. 

ELGIN — Clover. — The  inoculation  experiment  has  been 
a  great  success.  I  sowed  the  clover  with  oats.  The  part 
I  left  untreated  has  been  a  failure,  where  treated  there 
is  a  good  crop.  I  thought  when  I  sowed  it  it  would 
have  no  effect  on  the  corn  crop,  but  only  on  the  grass 
next  year,  but  I  am  glad  to  say  that  on  the  top  of  the 
field  which  is  inoculated,  where  the  land  is  very  poor 
and  no  depth  of  soil,  there  is  a  good  crop  of  oats  where 
it  was  never  anything  before.  The  neighbouring  farmers 
are  wondering  what  I  have  done  to  it.  On  the  part  of 
the  field  I  left  uninoculated  the  oats  are  not  nearly  so 
high  or  so  thick  as  where  it  is  inoculated. 

FORRES — Clover. — I  am  glad  to  say  that  the  crop  of 


220  THE  SPIRIT  OF  THE  SOIL 

inoculated  clover  is  the  best  we  have  ever  had,  quite 
double,  if  not  more,  than  usual,  and  it  has  grown  where 
in  one  part  clover  never  would  grow  before.  I  must 
congratulate  you  on  your  success,  and  trust  I  may  be 
allowed  to  have  some  more  inoculating  material  next  year. 
RUTHERGLEN — Beans. — On  April  17,  1907,  I  took 
i  pound  10  ounces  of  Bunyards'  Exhibition  Long  Pod 
Beans,  of  which  I  planted  i  pound  6  ounces  after  inocu- 
lating as  directed,  the  other  4  ounces  were  planted  un- 
inoculated  at  the  same  time.  The  former,  when  from 
3  to  4  inches  above  ground,  were  again  inoculated  with 
the  dilute  solution,  the  latter  were  not.  The  garden 
slopes  to  the  north  pretty  steeply,  and  the  soil  is  heavy 
clay,  which  a  month  before  planting  had  dug  into  it 
farmyard  manure  in  about  the  proportion  of  14  cart- 
loads per  acre.  Yesterday  (October  9)  I  took  20  stalks 
as  they  came  from  an  inoculated  and  a  non-inoculated 
row,  and  found  the  weight  of  all  the  pods  of  each  were 
7  J  pounds  and  i  pound  9  ounces  respectively,  and  of  the 
beans  alone  2f  pounds  and  £  pound.  The  sta]ks  from 
inoculated  seed  are  quite  remarkable  for  their  vigorous 
growth  both  in  weight  and  length,  and  if  attention  had 
been  given  to  pruning  of  side-shoots  the  harvest  of  pods 
would  in  the  end,  I  feel  quite  sure,  have  been  appreciably 
heavier,  although  even  as  it  is  it  is  quite  remarkable. 
The  stalks  are  still  green  with  a  considerable  show  of 
blossom,  although  at  this  late  season  they  must  soon 
shrivel  and  die  down. 

IRELAND. 

THURLES — Clover. — The  inoculation  experiment  is  a 
great  success.  All  the  clover  is  growing  wonderfully 
thick  through  the  barley,  though  it  is  said  locally  that 
clover  will  not  grow  in  this  townsland. 


APPENDIX  A  221 

KING'S  COUNTY. — Peas. — Inoculated  rows  have  borne 
most  excellent  crops,  much  better  than  in  former  years. 

Beans. — A  very  marked  difference  was  shown  in  growth 
of  the  broad  beans — those  which  I  had  not  inoculated 
being  much  smaller  and  fewer. 

During  the  year  reports  have  come  to  hand  of  various 
experiments  in  different  parts  of  the  country,  with  inocu- 
lating material  obtained  from  abroad.  In  many  cases 
excellent  results  have  been  obtained,  as  indicated  by  the 
three  following  reports : 


ENGLAND. 

ROTHAMSTED — Clover. — Land  which  was  known  to 
have  carried  no  leguminous  crop  for  the  last  50  years 
was  planted  with  red  clover  seed,  and  yielded  as  follows : 

Plot  A.  Inoculated  with  Hiltner's  preparation  from  Cwts. 

Germany           . .          . .          . .          . .          . .  76*4 

Plot  B.  Inoculated  with  Moore's  preparation  from 

America            . .          . .          . .          . .          . .  72-9 

Plot  C.  Uninoculated  ..  ..  ..  61-9 


SCOTLAND. 

WEST  OF  SCOTLAND  AGRICULTURAL  COLLEGE — Beans. 
— Professor  Wright  reports:  "  On  all  the  farms  (five)  on 
which  the  inoculation  proved  beneficial  the  increase  of 
crop  obtained  was  enough  to  give  a  very  satisfactory 
return  for  the  labour  and  cost.  An  average  increase  of 
304  pounds  grain  per  acre,  as  compared  with  3  \  cwts.  of 
straw,  shows  clearly  that  the  inoculation,  while  it  gave  a 
larger  crop  of  straw,  increased  the  yield  of  beans  in  a 
much  greater  degree,  and  hence  the  effect  of  this  ad- 
ditional treatment  has  been  to  enhance  still  further  the 


222  THE  SPIRIT  OF  THE  SOIL 

grain-producing  character  of  the  bean  crop.  The  average 
return,  amounting  to  about  4  Jbushels  beans  and  3  Jcwts. 
bean  straw  per  acre,  would  have  formed  a  sufficient 
return  for  a  much  higher  expenditure. 

"  But,  apart  from  one  failure,  and  making  due  allow- 
ance for  the  discrepancies  inseparable  from  field  experi- 
ments, the  results  on  the  whole  tend  to  show  that,  under 
suitable  conditions  and  on  ordinary  bean  soils,  the 
practice  of  inoculation  appears  likely  to  be  beneficial 
and  profitable." 

Lucerne. — At  the  College  Experiment  Station,  Kil- 
marnock,  experiments  on  the  inoculation  of  a  growing 
crop  of  lucerne  have  been  in  progress  during  the  past 
three  years.  A  growing  crop  of  lucerne  was  subdivided 
into  three  plots.  All  received  equal  dressings  of  super- 
phosphate and  potash;  but  as  regards  nitrogen,  A  had 
no  nitrogenous  manure,  B  was  dressed  with  nitrate  of 
soda  at  the  rate  of  2  cwts.  per  acre,  C  was  inoculated  with 
culture  material  from  Germany.  Last  year  the  green 
produce  from  each  plot  was  carefully  weighed,  and  gave — 

Tons.    Cwts.     Qrs. 

A.  No  Nitrogen  . .          . .          . .       7         o         3  per  acre. 

B.  Two  cwt.  Nitrate  Soda        . .        9         8         2 

C.  Inoculated     ..          ..          ..12         5         p         ,, 

IRELAND. 

Vetches. — The  inoculated  seed  produced  23  tons  of 
vetches  (cut  green)  per  acre,  while  the  uninoculated  pro- 
duced only  ii  tons  7  cwts.;  showing  an  increase  of 
ii  tons  13  cwts.,  or  more  than  double,  in  favour  of 
inoculation. 


APPENDIX  B 

EFFECTS  OF  TREATING  PLANTS  WITH 
HUMOGEN 

THE  following  are  among  the  reports  that  have  been 
received  from  growers  as  to  the  effect  of  using  bacterized 
peat.  The  first  groups  of  results  are  those  obtained  by 
Mr.  Machen  (who  is  now  assisting  Professor  Bottomley) 
from  experimental  plots  at  Eton  Experimental  Gardens 
in  1913  and  1914.  In  some  instances  it  has  been  possible 
to  tabulate  the  results.  As  further  reports  are  received 
from  growers  they  will  be  added  to  this  appendix  in 
subsequent  editions. 

ETON  EXPERIMENTAL  GARDENS  (1913-1914). 

(Report  by  Mr.  Machen.  The  first  report  was  quoted  by  Pro- 
fessor Bottomley  in  the  lecture  he  delivered  before  the 
Royal  Society  of  Arts  in  1914.) 

The  whole  plot  was  51  feet  long  by  36  feet  wide.  The 
plot  was  divided  across  its  breadth  into  three  equal 
portions  of  15  feet  each,  and  a  smaller  portion  of  6  feet. 
This  gave  three  plots  of  60  square  yards  each,  and  a 
small  plot  of  24  square  yards.  These  plots  were  treated 
as  follows:  Plot  i,  complete  artificial  manure  (top-dress- 
ing), 4  ounces  per  square  yard;  Plot  2  (small  plot),  no 
manure;  Plot  3,  bacterized  peat  (top-dressing),  9  ounces 
per  square  yard ;  Plot  4,  one  ton  farmyard  manure  (half 
dug  in  subsoil  and  half  in  top  spit). 
223 


224 


THE  SPIRIT  OF  THE  SOIL 


The  rows  of  plants  ran  across  each  of  these  four  plots. 
As  each  crop  matured  careful  weights  were  taken,  and 
are  shown  in  the  table  on  p.  225. 

The  percentage  increase  of  the  produce  from  the  peat- 
treated  plots  over  those  with  no  manure,  artificials,  and 
farm  dung  is  as  follows : 


No  Manure. 

Artificials. 

Farm  Dung. 

Per  Cent. 

Per  Cent. 

Per  Cent. 

Potatoes 

123 

75 

41 

Turnips 

IOO 

47 

25 

Beet.  . 

281 

54 

43 

Onions 

no 

no 

46 

Carrots 

260 

20 

28 

It  will  be  noticed  that  in  all  cases  the  yields  are  small. 
This  is  accounted  for  by  Mr.  Machen  in  the  following 
notes : 

1.  Sandy  soil  over  gravel.     No  manure  for  nine  years, 
and   had   been   continuously   cropped   with   potatoes, 
followed  by  brassica. 

2.  The  previous  season  (1912)  crops  were  a  complete 
failure.     Land  as  nearly  exhausted  as  possible. 

3.  The  mixture  of  artificials  used  usually  gives  better 
results  than  dung,  but  owing  to  the  exceptionally  dry 
spring   of    1913    the    wet    farmyard    manure   had    an 
advantage. 

4.  All  the  crops  were  much  below  the  normal  owing  to 
— (a)  starved  land ;  (b)  exceptionally  dry  season  on  a 
hot,  dry  soil.     Potatoes  were  all  first  earlies. 

5.  The  land  was  specially  selected  for  testing  food 
values  on  an  exhausted  soil. 

In  1914  experiments  were  carried  out  on  similar  lines, 
giving  the  results  tabulated  on  p.  227.  A  striking  feature 


APPENDIX  B 


225 


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226  THE  SPIRIT  OF  THE  SOIL 

of  them  was  the  residual  effect  of  peat  on  the  plots  that 
had  been  treated  in  the  previous  year.  As  regards  these 
plots,  the  last  in  the  table,  no  fresh  humogen,  artificials  or 
manure  were  applied. 

MID-SURREY  GOLF  COURSE. 

The  remarkable  results  obtained  on  the  Mid- Surrey 
Golf  Course  are  described  as  follows  by  the  Editor  of  the 
Garden,  writing  in  Country  Life  on  November  i,  after 
inspecting  the  greens  in  the  company  of  Mr.  Lees,  the 
groundsman  at  Mid-Surrey:  "  The  first  to  be  dressed 
was  a  practice  green,  which,  owing  to  the  very  hard  wear 
to  which  it  is  subjected,  and  the  fact  that  it  is  on  sand, 
always  gives  a  great  deal  of  trouble,  particularly  in  the 
autumn.  This  green  was  treated  on  August  28,  and  at 
that  time  was  in  a  very  worn  condition.  Now  (Novem- 
ber i)  it  is  as  perfect  as  a  green  could  be,  the  turf  being 
very  close  and  hard,  and  of  a  particularly  healthy  colour^ 
Near  to  this  practice  green,  and  also  on  sand,  is  an 
undulating  green  that  Lees  assured  me  has  always  been 
a  worry  to  him  at  this  season.  This,  when  dressed  with 
the  prepared  peat  a  little  more  than  a  fortnight  ago, 
was  very  brown  in  places,  but  now  the  brown  patches 
have  almost  disappeared,  and  the  turf  is  very  healthy, 
and  of  excellent  substance.  A  third  green,  also  of  an 
undulating  character,  was  treated  on  Tuesday  of  last 
week,  and  three  days  later  was  showing  signs  of  improve- 
ment. After  experimenting  with  different  quantities  to 
ascertain  the  proper  amount  to  use — 2,  4,  6,  10,  and 
12  ounces  per  square  yard  respectively — Lees  has  come 
to  the  conclusion  that  3  ounces  per  square  yard  produces 
the  most  satisfactory  results.  This  is  applied  in  a  pul- 
verized state  as  a  top-dressing,  and  for  the  first  few  days 


APPENDIX  B 


227 


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L 


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•  a 


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11 


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228 


THE  SPIRIT  OF  THE  SOIL 


seems  to  open  up  the  soil  and  to  let  the  grass  through, 
after  which  this  slight  sponginess  disappears.  Not  only 
have  these  dressings  had  a  most  remarkable  effect  on  the 
blades  of  the  grasses,  but  root  growth  has  also  been 
increased  to  a  very  considerable  extent." 


TABULATED  RESULTS. 

ADDLESTONE. 
DATE,  JUNE  27,  1915. 


Crop. 

Quantity. 

How  applied. 

Result:  Weights 
when  possible. 

Tomatoes 

I-IO 

Mixed  in  soil 

Tomatoes  treated  when 
put  into  48  pots  took 
the  lead  of  the  others. 
Very  pronounced  with- 
in a  week,  and  still 
retain  their  extra 
vigour,  etc. 

THOMAS  STEVENSON,  Woburn  Place  Gardens,  Addlestone. 

BIRMINGHAM. 
DATE,  JULY  17,  1915. 


Auricula 


Mixed  in  soil 


I  find  that  auriculas 
potted  with  humogen 
are  quite  free  from 
woolly  aphis,  and  those 
not  so  potted  are  still 
showing  same. 

A  friend  I  gave  some  to 
finds  the  growth  bet- 
ter, and  confirms  what 
I  say  with  regard  to 
aphis. 


T.  E.  ASTON,  25,  Grosvenor  Road,  Handsworth,  Birmingham. 


APPENDIX  B 


229 


ILFORD. 
DATE,  OCTOBER  17,  1914. 


Crop. 

Quantity. 

How  applied. 

Result  :  Weights 
when  possible. 

Flowers  in 



Periodical 

I  had  a  hanging-basket 

hanging. 

top-dressing 

containing    geraniums 

basket 

and   asparagus   ferns, 

to  which   I  have  ap- 

plied    periodically     a 

dressing,     with    most 

remarkable       results. 

Under    ordinary    cir- 

cumstances   I    should 

have  been  obliged  to 

replenish    the    basket 
with    later    flowering 

plants   at   least  once. 

but    under    humogen 

we  have  had  a  succes- 

sive crop  of  new  spikes 

and  buds,  with  the  re- 

sult  that  the  plants, 

which  were  put  in  last 
May,  are  still  flower- 

ing, October  17,  1914. 

J.  B.  P.  HARRISON,  Ilford. 

KEW. 
DATE,  1913. 


Pot  plants, 
in  variety 


1-9 


Mixed  in  soil 


The  plants,  beyond  or- 
dinary details,  had  no 
special  attention  dur- 
ing growth  other  than 
that  devoted  to  start- 
ing them;  after  a  fort- 
night or  so  they  were 
left  to  themselves. 
The  results  in  some 
cases  were  extraordin- 
ary, and  not  compar- 
able with  those  ob- 
tained from  ordinary 
nitrogenous  manures, 
the  root  development 
being  very  marked. 


MR.  COUTTS,  the  Royal  Gardens,  Kew :  Journal  of  Royal 
Society  of  Arts,  March  13,  1914. 


230 


THE  SPIRIT  OF  THE  SOIL 


SLOUGH. 
DATE,  JULY,  1913. 


Crop. 

Quantity. 

How  applied. 

Result:  Weights 
when  possible. 

Tomato 

A.  Watered 

, 

A.  Equal  to  D. 

with  bac- 

teria once 

B.  Rough 

— 

B.  25  per  cent,  superior 

humogen 

to  A  and  D. 

placed  on 

crocks 

C.  i-io 

Mixed    with 

C.  Equal  to  B. 

soil 

D.  Control 

1-4  old  rot- 

D. Equal  to  A,  inferior 

ted     dung. 

to  B  and  C. 

Fed      with 

Chelsea 

Horticul- 

tural Ferti- 

lizer  every 

three  days  J 

General  Remarks. — Tomato  plants  hi  pots  gave  better  results 
with  far  less  trouble  than,  any  other  known  method  of  feeding,  at 
a  minimum  of  expense. — J.  ALLGROVE,  Langley,  Slough. 


SLOUGH — Continued. 
DATE,  JULY,  1914. 


Garden 
peas 


Water 
tract 


4  gallons  to 
60  yards 


The  plants  responded 
to  its  application 
quickly,  the  growth 
was  much  stronger, 
and  continued  after 
untreated  plants  were 
quite  yellow.  The 
pods  were  much  finer 
and  more  abundant. 


General  Remarks. — Three  rows,  each  20  yards,  untreated; 
weight  of  dry  seed,  18  Ibs.  Three  rows  each  20  yards,  treated; 
weight  of  dry  seed,  28  Ibs.  Percentage  increase,  55-5  per  cent. 
Increased  value,  i8s.  3d. — JOHN  ALLGROVE,  Langley,  Slough. 


APPENDIX  B 


231 


WINDSOR. 
DATE,  JUNE,  1915. 


Crop. 

Quantity. 

How  applied. 

Result  :  Weights 
when  possible. 

I.  Pteris 

I-IO 

Mixed  in  soil 

I  repotted  a  few  Pteris 

Major 

Major  on  August  20  in 

humogen  mixture.     I 

think    the    growth    is 

wonderful.     They  are 

already    (October    27) 

much  finer  plants  than 

I    usually   get   in   six 

months. 

,  From  the  small  amount 

I  had  I  think  the  re- 

sult     is      wonderful. 

During      my      thirty 

2.  Maiden- 

I-IO 

Mixed  in  soil 

years'     experience     I 

have       never       come 

3.  Aspara- 

across    anything     to 
show    such    quick    re- 

gus 
a.  Sprengeri 

I-IO 

Mixed  in  soil 

J  suits.   Twenty-six  days 
I  after  potting,  maiden- 

b. Plumosa 

I-IO 

Mixed  in  soil 

hair   have   made   nice 
plants,     while     those 

without  are  just  mak- 

ing a  start. 

The  growths  of  aspara- 

gus are  much  stronger 

and    a    much    better 

colour. 

F.  DAVIS,  Nurseryman,  St.  Leonard's  Road,  Windsor. 

WINDSOR— Continued. 
DATE,  AUGUST  4,  1915. 


Begonia 


I-IO 


Mixed  in  soil 


Extraordinary  profu- 
sion of  bloom.  Over 
100  blooms  on  a  semi- 
double  variety,  quite 
twice  the  amount  of 
growth  and  bloom 
over  untreated.  Very 
free  and  vigorous,  with 
healthy  green  leaves. 


232 


THE  SPIRIT  OF  THE  SOIL 


WINDSOR— Continued. 


Crop. 

Quantity. 

How  applied. 

Result  :  Weights 
when  possible. 

Celery 





Never  had  such  splen- 

did plants,  now  aver- 

aging 30  inches  high, 

deep   rich   green   foli- 

age, and  perfectly  free 

from  fly.    (Aug.,  1915.) 

Kale 

4  ozs.  per  sq. 

Mixed  in  soil 

Grown  in  ash-heap,  soil 

yd. 

more  than  half  ashes 

and  broken  pots. 

"  Growing  wonderfully 

strong." 

Onions 

6  ozs.  per  sq. 
yd. 

Mixed  in  soil 

Crop    promises    to    be 
half  as  heavy  again  as 

untreated. 

Carnation 

I-IO 

Mixed  in  soil 

Growth  was  both  vigor- 

ous and  free,  without 

being  soft.    The  quan- 

tity   of    growth    and 

flower  was  remarkable. 

Carnation 

— 



Plant    in    border    col- 

eel-worm 

lapsed     through     eel- 

worm.   The  soil  where 

plant  was  growing  re- 

ceived 3  ozs.  of  humo- 

gen    stirred    in,    and 

* 

new  plant  from   pot, 

planted  in  early  May. 

Now    (August   4)    the 

plant      is      perfectly 

healthy,  and  without 

a  trace  of  eel-  worm. 

Runner 

4  ozs.  per  yd. 

Mixed  in  soil 

More  vigorous  growth, 

Beans 

run 

thicker     stems,     and 

heavier  crop.     Better 

quality   produce;    full 
of      vitality,      deeper 

green      foliage,      and 

much  larger  leaves. 

Beans  earlier  i  week. 

Average  length,  12  in. 

Untreated,  9  in. 

40    plants    averaged    £ 
bushel,     gathered     i| 

bushels  per  week. 

Every  bloom  set,  result- 

ing in  large  clusters. 

APPENDIX  B 

WINDSOR— Continued. 


233 


Crop. 

Quantity. 

How  applied. 

Result  :  Weights 
when  possible. 

Asters 

1-20  ? 

Mixed  in  soil 

When  pricked  out  into 

boxes,  plants  grew  at 

tremendous  rate  and 

produced  very    much 

stronger  plants.     The 

blooms     were     ready 

thirteen    days    earlier 

on     stems     averaging 

15  in.  as  against  10  in. 

on  untreated. 

The  colour  of  the  foliage 

was  a  rich  blue  green, 

and  plants  were  very 

stiff  and  sturdy. 

Stocks 

1-20  ? 

— 

As    asters.       Fourteen 

days    earlier,    heavier 

flowers,  and  very  fine 

plants. 

Roses 

4  ozs.  per 

Lightly 

Growth   both   stronger 

plant 

forked  in 

and  freer,  the  breaks 

being     very     numer- 

ous.     The    colour    of 

both       foliage       and 

blooms  greatly  intensi- 

fied, particularly  with 

Dean  Hole  and  Lyons. 

Treated  and  untreated, 

growing  side  by  side, 

almost  appeared   dis- 

tinct varieties. 

Won  3  firsts,  I  third,  I 

cup  —  5  entries. 

G.  W.  BISHOP  AND  SONS,  Windsor. 

Tomatoes 

i—  20 

Mixed  in  soil 

Plants       grew      away 
quickly,  making  small 
dark  green  foliage,  and 
setting     fruit     freely. 
Treated     plants     are 
better    25    per    cent., 
both  in  quantity  t  and 
quality  of  fruit.    \ 
Fruits    were    ripej  at 
least      three      weeks 
earlier  than  untreated. 

234  THE  SPIRIT  OF  THE  SOIL 

WINDSOR— Continued. 


Crop. 

Quantity. 

How  applied. 

Result:  Weights 
when  possible. 

Garden 

3  ozs.  per  yd. 

Top-dressed, 

Treated      rows     much 

peas 

run 

hoed  in 

stronger  in  haulm,   a 

better  colour,  and  with 

a  heavier  crop  of  well- 

filled  pods. 

Sweet  peas 

3  ozs.  per  yd. 

Lightly  dug 

Taller,     stronger,     and 

run 

in 

greener  ;    flower-stems 

averaged  3  in.  longer 

than  untreated.  Colour 

of    flower    intensified. 

Continued        growing 

longer. 

Coffee  -  col- 

Watered in 

When  growth  for  sea- 

oured liquid 

son     had     apparently 

finished     and     plants 

were  yellow,  a  water- 

ing   of    strong    liquid 

produced  new  growth, 

which  a  fortnight  later 

gave  good  blooms  for 

sale. 

F,  DAVIS,  Nurseryman,  Windsor. 


Sweet  peas 

A  small  quan 

tity  sprinkled 

There    was    a    distinct 

amongst  pla 

nts  and  hoed 

gain  in  height  ;  vigour 

in 

of    stem    and    foliage 

very      marked,      and 

colour  and  veining  in 

flowers  distinctly  im- 

proved. 

Won     Bide    Cup     and 
silver-gilt     medal     at 

National    Sweet    Pea 

Show,     1915,    besides 

securing    5    firsts,     2 

seconds,        i        fifth, 

N.S.P.S.—  8  entries,  8 

prizes. 

G.  W.  BISHOP  AND  SONS,  Windsor. 

APPENDIX  B  235 


OTHER  RESULTS  OF  WHICH  LESS  EXACT 
DETAILS  ARE  AVAILABLE. 

BUCKS. 

WINDSOR. — The  Potatoes  treated  with  the  bacterial 
culture  gave  an  increase  of  35  per  cent,  over  the 
untreated ;  and  the  Lettuce  were  practically  100  per  cent, 
better. 

ESSEX. 

RAYLEIGH — Onions. — Inoculated,  8  pounds  3  ounces; 
uninoculated,  5  pounds,  14  ounces.  Increase,  39  per 
cent. 

GUERNSEY. 

Tomatoes. — Inoculated  144  plants,  gave  yield  of 
8*06  pounds  per  plot;  uninoculated  1,340  plants,  gave 
yield  of  7-02  pounds  per  plot.  Increase,  14-8  per  cent. 

KENT. 

CATFORD. — The  Rose-trees  watered  with  the  bacterial 
culture  yielded  quite  twice  as  many  blooms  as  the 
untreated  trees. 

W.  RAMSGATE. — Tomatoes — where  treated  the  foliage 
was  a  darker  green,  and  produced  an  enormous  crop, 
double  that  of  the  plants  not  treated. 

MIDDLESEX. 

GREENFORD  GREEN  (AUGUST,  1915) — Tomatoes. — 
Two  shallow  boxes  were  taken.  To  one  56  pounds  of 
dung  were  added,  to  the  other  2  pounds  of  humogen. 
Three  plants  were  grown  in  the  first  and  four  in  the 
second.  Both  sets  of  plants  are  far  superior  to  others 


236  THE  SPIRIT  OF  THE  SOIL 

grown  in  the  same  house  without  fertilizers.  There  is 
not  much  to  choose  between  the  humogen-treated  and 
the  dung-treated  plants  in  size,  but  those  treated  with 
humogen  are  yielding  ripe  tomatoes,  while  those  treated 
with  dung  are  only  beginning  to  ripen.  The  fruits  on  the 
humogen-treated  plants  are  generally  in  a  more  advanced 
stage. 

"  Having  had  such  extraordinary  results  during  the 
past  season  by  the  use  of  humogen,  I  thought  perhaps 
the  following  particulars  might  be  of  interest  to  you : 

"  Sweet  Peas. — I  purchased  the  seeds  from  reliable 
seedsmen,  potted  them  last  October,  and  planted  the 
seedlings  out  the  second  week  in  April  as  follows:  On 
the  more  favourably  situated  side  of  the  garden  I 
planted  eight  seedlings  to  form  clumps  of  2  feet  diameter. 
I  treated  the  ground  in  January  with  a  well-known  sweet 
pea  manure,  and  when  the  plants  began  to  show  bud  I 
watered  them  with  liquid  manure  made  from  half  cupful 
of  sweet  pea  manure  and  ij  gallons  of  water.  On  the 
other  side  of  the  garden  I  planted  eight  seedlings  as 
before,  but  treated  the  ground  this  time  with  humogen, 
something  like  i  in  10.  When  these  plants  began  to  show 
bud  I  watered  them  with  liquid  manure  made  from  one 
cupful  of  humogen  to  i  J  gallons  of  water.  This  I  gave 
in  each  case  once  a  week.  Both  clumps  are  still  in 
flower,  and  approximate  heights  are :  Sweet  pea  manure, 
8  feet  6  inches ;  humogen  plants,  10  feet.  I  have  had 
considerably  more  blooms,  larger  size,  and  longer  and 
stronger  stems  on  the  ones  treated  with  humogen  than 
those  treated  with  sweet  pea  manure.  The  neighbours 
around  are  astonished  at  them,  and  no  wonder.  I  have 
never  had  such  plants  before. 

"  Dahlias. — These  were  treated  with  humogen,  with 


APPENDIX  B  237 

the  result  that  I  have  magnificent  blooms  as  regards 
quantity,  size,  and  shape. 

"  Roses. — These  along  with  dahlias  have  been  special 
favourites  of  mine  for  some  years  past.  For  the  last 
three  years  I  have  had  some  good  blooms,  but  nothing 
like  I  have  had  this  year.  The  only  way  I  can  account 
for  it  is  the  use  of  humogen.  To  sum  up,  I  have  been  a 
keen  amateur  gardener  for  many  years,  and  have  tried 
many  fertilizers,  but  up  to  the  present  I  have  struck 

nothing  like  humogen. 

/'T.  ATKINSON. 

"CARNWATH, 

"CHATSWORTH  AVENUE, 

"WEMBLEY  HILL, 
"August  4,  1915." 

HARROW — Onions. — Treated  rows,  41  pounds;  un- 
treated rows,  29  pounds.  Increase,  41  per  cent. 


RUTLAND. 

OAKHAM — Mangolds. — Two  rows,  9  yards  long. 
Treated,  7  stones  10  pounds;  untreated,  5  stones 
2  pounds.  Increase,  50  per  cent, 

Strawberries  in  pots  and  out  of  doors  both  showed  an 
improvement. 

Sweet  Peas  more  still. 

Peas  and  Beans. — These  showed  a  more  vigorous 
growth. 

Early  Potatoes  gave  a  heavier  crop  and  much  brighter 
sample  than  those  treated  with  manure  only. 

Celery  were  more  free  from  fly,  and  had  a  better 
growth. 


238  THE  SPIRIT  OF  THE  SOIL 

SURREY. 

"  In  a  plot  of  ground  used  as  a  vegetable  garden  I  had 
obtained,  up  to  this  year,  very  poor  results.  This  year 
I  determined  to  use  humogen;  the  results  have  been 
quite  remarkable.  The  largest  of  last  year's  turnips  only 
reached  the  size  of  a  fairly  large  strawberry;  this  year 
I  have  had  turnips  the  size  of  one's  fist,  and  the  smallest 
are  larger  than  the  largest  of  last  year's  crops.  I  am 
having  very  much  better  results  with  tomatoes,  beans, 
and  lettuce,  and  I  can  without  hesitation  state  that  it 
can  only  be  due  to  the  feeding  properties  of  humogen. 


'GEORGE  F.  WEST. 


"4,  HILBURY  ROAD, 
"  BALHAM, 

"August  4,  1915." 


LIST  OF  PAPERS 

BY  PROFESSOR  WILLIAM  BEECROFT  BOTTOMLEY, 
M.A. 

DEALING  WITH  BACTERIAL  FIXATION  OF  NITROGEN  AND  THE 
EFFECT  OF  SOLUBLE  HUMATES  IN  THE  SOIL. 

"  The  Assimilation  of  Nitrogen  by  Certain  Nitrogen-Fixing  Bac- 
teria in  the  Soil."     (Proc.  Roy.  Soc.  B.,  vol.  Ixxxii.,  1910.) 

"  Some  Effects  of  Bacterio toxins  on  the  Germination  and  Growth 
of  Plants."     (Report  Brit.  Association,  1911.) 

"  The  Fixation  of  Nitrogen  by  Free-living  Soil  Bacteria."    (Re- 
port Brit.  Association,  1911.) 

"  Some  Conditions  influencing   Nitrogen   Fixation   by  Aerobic 
Organisms."     (Proc.  Roy.  Soc.  B.,  vol.  Ixxxvi.,  1912.) 

"  Some  Effects  of  Humates  on  Plant  Growth."     (Report  Brit. 
Association,  1912.) 

"  Ammonium  Humate  as  a  Source  of  Nitrogen  for  Plants."    (Re- 
port Brit.  Association,  1913.) 

"  The  Effect  of  Soluble  Humates  on  Nitrogen  Fixation  and  Plant 
Growth."     (Report  Brit.  Association,  1913.) 

"  The  Bacterial  Treatment  of  Peat."     (Jour.   Roy.   Soc.  Arts, 
vol.  Ixii.,  1914.) 

"  Some  Accessory  Factors  in  Plant  Growth  and  Nutrition." 
(Proc.  Roy.  Soc.  B.,  vol.  Ixxxviii.,  1914.) 

"  The  Significance  of  Certain  Food  Substances  for  Plant  Growth." 
(Annals  of  Botany,  vol.  xxviii.,  1914.) 

"  The  Formation  of  Humic  Bodies  from  Organic  Substances." 
(Biochem.  Jour.,  vol.  ix.,  1915.) 

"A  Bacterial  Test  for  Plant-Food  Accessories  (Auximones)." 
(Proc.  Roy.  Soc.  B.,  vol.  Ixxxix.,  1915.) 


239 


INDEX 


ACCESSORY    food    bodies,    94, 
96  sqq.     See  also  Vitamines 
and  Auximones 
Acid  soils,  171  $<?<?. 
America   and   inoculation,    53 

sqq. 
and    nitrobacterine,    136, 

137 

Amides,  133 

Ammonia  from  manure,  27 
Annus  mirabilis,  19 
Antiseptics  and  soil  organisms, 

3°»  49 
Auximones,   94,   96  sqq.,    158, 

191 

and  animals,  117 
derivation  of,  112 
test  for,  113  sqq. 
Azotobacter,    28,    88,    89,    112 
sqq.,  139,  152 

Bacillus  radicicola,  60  sqq.,  Si, 
82,  88,  139,  152 

Bacteria  in  the  soil,  numbers 
of,  25.  See  also  Nitrogen- 
fixing  organisms,  Nitrifying 
organisms,  Azotobacter,  Ba- 
cillus radicicola,  Humogen, 
Humus,  etc. 

Bacterized  peat.  See  Humo- 
gen 

Beriberi,  99  sqq.  See  also  De- 
ficiency diseases 

Beyerinck,  89 

Board  of  Agriculture,  54  sqq. 

Carbohydrates,  133 
Carbon  as  plant  food,  5 

dioxide  from  manure,  27 
Cavendish  and  nitric  acid,  6 
Chelsea   Physic   Gardens,    ex- 
periments, 1 02 
Condensation,  129,  130 
Clostridium  pasteurianum,  89 


Coal  consumption  in  Eng- 
land, 3 

Cooke,  1 60 

Coutts  on  Kew  experiments, 
141 

Crookes  on  the  nitrate  prob- 
lem, 5 

Dachnowski  on  peat,  31  sqq. 

Deficiency  diseases,  99  sqq.  See 
also  Beriberi,  Scurvy,  Vita- 
mines,  etc. 

Dehydration,  128  sqq. 

Detmer  and  humus,  80 

England  and  the  food-supply, 

ii  sqq. 
Eykman  and  beriberi,  99 

Fats,  133 

Fielding  and  England's  food- 
supply,  12  sqq. 

Food-supply  in  Europe,  n  sqq. 
Funk,  99  sqq. 

Hellriegel,  50  sqq. 

Holmes,  experiments  by,   144 

sqq.,  153,  163 
Hopkins,  in  sqq. 
Humic  acid,  69  sqq. 

colloidal       properties 

of,  92 

substances.     See  Humus 
Humogen  and  its  results,   81 

sqq.,  179  sqq.,  225  sqq. 
application  of,  169  sqq. 
cautions  for  use  of,    197 

sqq. 
model  experiments   with, 

200  sqq. 

preparation  of,  150  sqq. 
prizes   gained    with,    184, 

194.  195 
testing  of,  135  sqq. 


241 


242  INDEX 


Humus,  64  sqq. 
Hydra tion,  128  sqq. 

Inoculation,  results  of,  53  sqq. 
See  also  Humogen,  etc. 

Keeble,  158 

Kew  results,  102,  140  sqq.,  178 
sqq.  See  also  Humogen, 
Newspaper  criticisms,  etc. 

Lawes,  influence  on  agricul- 
ture, 48 

Lees,  226 

Leguminous  plants  and  nitro- 
gen, 48  sqq.  See  also  Nitro- 
bacterine,  Nitrogen-fixation, 
etc. 

Liebig,  influence  on  Agricul- 
ture, 47  sqq. 

Lipman,  89 

Machen,  93,  95,  225,  227 
Malthus  and  the  food-supply,  4 
Manure  and  auximones,  116 

decomposition  of,  26 
Moore,  101  sqq. 

Mess  culture  experiments,  146, 
163 

Newspaper  criticisms,  159  sqq. 
Nitragin,  53  sqq. 
Nitrate  deposits,  4 

problem,  I  sqq. 
Nitrobacterine,  56  sqq. 

and  America,  137,  156 

difficulties  with,  137  sqq. 

results  with,  205  sqq. 
Nitrogen  as  plant  food,  5 

balance-sheet,  7 

fixation,  46  sqq.,  88 

-fixing  organisms,   effects 

of,  on  soil,  92 
and  symbiosis,  90 
Noble  and  inoculation,  53  sqq. 

Oxidation,  128  sqq. 

Pasteur  and  bacteria,  49 
Peat,  31  sqq. 


Peat,  a  <  omplete  plant  food,  140 

bac  erization  of,  87  sqq. 

comj  irison     with     other 
manures,  86 

decomposition  of,  83  sqq. 

extract,  85 

uses  of,  40  sqq. 
Phosphates  and  humogen,  92 

and  manure,  28 
Phosphotungstic  fraction.    See 

Auximones 

Plant  inoculation.     See  Inocu- 
lation 
Potash  and  humogen,  92 

and  manure,  28 
Prazmowski  and  inoculation,  53 
Proteids,  133 
Protozoa,  29 

Reduction,  128  sqq. 
Rice.     See  Deficiency  diseases 
Root-nodules.     See    Legumin- 
ous plants 

Rosenheim,  102  sqq.,  158 
Rothamsted,  48  sqq. 

Schloesing  and  Miintz,  experi- 
ments, 49 

Scurvy,  101  sqq. 

Silver  fraction.  See  Auxi- 
mones 

Standard  bread,  102  sqq.,  118 

Starling  and  chemistry  of  the 
blood,  98 

Sterilization  of  soil,  153 

Symbiosis  and  nitrogen-fixing 
bacteria,  90.  See  also 
Leguminous  plants 

Van  Bemmelen  and  humus,  80 
Vitamines,  94,  96  sqq. 
Voelcker  on  peat,  44 
Vordermann  and  beriberi,  99 

Ward  and  nodule  formation,  52 
Watson- Wemyss,  100  sqq. 
Weathers,    experiments,     148, 

149 

Wheat.     See  Food-supply  ^ 
Winogradsky,  89 


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